2005 GMC Sierra, Lights Flicker or Pulsate

This 2005 GMC Sierra came in with the complaint that when the vehicle is started cold, the headlights, dash lights and dome light will flicker or pulsate. As the system runs the problem diminishes but never goes fully away. This is a common complaint on many Cadillac, Chevrolet and GMC full sized trucks and suv’s. I am glad I finally got a chance to test and find the root cause of this issue.

Since I was pretty sure that this was a charging system fault, I connected my tester to the battery and noted that the volts and amps readings were fluctuating as well. From here I took out my 8 gauge jumper wire and connected it to the negative battery terminal and then to the alternator frame. No change. I then connected it to the battery positive terminal and then to the alternator output terminal. No change. This test is a low tech way of checking for a poor ground or power connection condition. It is VERY IMPORTANT that the jumper wire always be connected to the battery first and then to the alternator. If there is a problem there WILL be a spark. The bigger the problem the bigger the spark. A spark near a battery can result in an EXPLOSION. It should be common knowledge that an explosion can maim or kill you! If this does not resonate with you, close the hood and take your vehicle to someone that does understand.

Keep in mind that some minor flickering is normal and is due to the changes in output voltage of the alternator as controlled by the PCM. This vehicle had a swing in voltage of up to .8 (eight tenths) of a volt. That is not normal.

There was no change during the above testing so it was clear to me that there was not an external connection problem. I did however notice that the output stud at the rear of the alternator was quite warm. I decided to take a temperature reading and it was at 162 degrees F.

I then took a reading at the stator laminations and found a much cooler reading of 118 degrees F. The engine had already been running about 5-6 minutes at this time.

After about 10 minutes of operation the stator was at 124 degrees F.

The output stud was now at 181 degrees F.

After fifteen minutes the stator was at 146 degrees F.

The highest temperature reading I got at the alternator output stud was 195 degrees F. Although the highest reading I got a picture of was 192.  Just to be sure, I removed the cable from the alternator and checked for any signs of looseness or corrosion that could build heat. There was no problem with the connection so the issue is internal to the alternator.

Since it is relevant I wanted to point out that the outside temperature was in the low fifties, as indicated by the thermometer in the rear view mirror.

After installing a new alternator I rechecked the readings and this is what I found in the first 2-3 minutes.

After 5 minutes.

After 15 minutes of running.

I also want to point out that in order to maintain the same load on the old and the new alternators, I turned the headlights on, switched the blower to the highest speed and turned on the rear window defogger.

From my nearly forty years of starter and alternator rebuilding, the problem will be in this connection in the positive rectifier plate where the output stud is pressed in. I plan on disassembling this alternator further to see the actual problem but that will be for another day.

From an installer viewpoint, if you are replacing the alternator for the reasons outlined in this article, you will need to make sure that the replacement alternator has had the rectifier fully serviced or replaced.

From a rebuilder’s perspective, if no obvious problem is found during testing of the core (you do test your cores before disassembly, right?), make sure that you either fully disassemble the rectifier to correct any potential problems there or simply install a new rectifier assembly. You may also want to incorporate temperature testing of the output stud with a load on the alternator for 5 -15 minutes. This will prevent comebacks and maintain your reputation.

2003 Chevrolet Silverado, Changing The Battery

This 2003 Chevrolet Silverado happens to be my personal vehicle and today I decided to test the battery as cool weather is upon us in South Carolina. The battery failed a load test as expected. I have heard the cranking sound slightly off key for the past few weeks. Yes, I can detect/hear a weak battery in the noise the starter makes while cranking the engine.

This repair article may seem quite mundane but there are some key points about maintaining system memory, choosing the correct battery and small details that can make a world of difference  in the reliability of your vehicle.

The first step in replacing a battery in a modern automobile is to set up a battery back up system. This maintains all of the memory in the computer systems. This is important for things like idle control and shift patterns. It also maintains things like radio stations, clocks and temperature settings.

Chevrolet created places that make it easy to perform this task. An aluminum tab near the alternator marked GND. This is of course where the ground cable attaches. There is a red plastic housing marked Battery(+). There is a cover that has to be opened to expose the cable connection. The positive cable of the jump box connects there. If your jump box is like mine make sure you remember to actually turn the switch on.

Now that the battery back up is in place it is time to start removing the battery. There is s fender brace with two bolts that hold it in place.

Both have 10 mm heads.

With the brace/bar out of the way it is time to switch to a 13 mm socket and add an extension.

This is the plastic hold down and 13 mm headed bolt that I was removing in the above picture.

Although I am showing removing the red/positive cable in the next picture, I do want to emphasize that the ground should always be disconnected first.

It takes a little bit of wrestling around to lift that battery up and out of the hole. Keep in mind that since we have a battery back up in place the red/positive cable is actually still hot/powered.  Since a battery normally only comes out of a vehicle every 3-6 years it is a good idea to at least clean the dirt out of the battery tray. I always use a shop vacuum to clean the battery tray.

Since this is my truck and I had enough time, I also wire brushed the tray to remove the loose dirt and rust.

I also spayed some black enamel paint on the tray to seal it. If I would have had more time I would have removed the tray, cleaned it in the glass bead cabinet and then primed and painted it. I am a bit OCD but not too bad today. Also note that I have placed the red plastic cap over the exposed battery bolt in the red battery cable end.

These batteries have a foam insulator that installs over the battery. Be sure that you transfer it from the old battery to the new battery.

It can be slid in either direction but today I pulled it off from the bottom, so there would be less chance of tearing it.

Installed on the new battery.

Be careful when installing the battery into the tray as the positive lead is still hot/powered.

I use dielectric grease on the battery posts.

I fill the void between the lead post and the plastic case. I also wipe some across the face of the metal.

When tightened any excess grease will be pushed out. I wipe off the excess with a  rag or my finger.

Another trick is to use anti-seize compound on the threads of the battery hold down bolt.

Make sure that the hold down is properly installed and tight. A loose battery will not last as long as a secured battery. The excessive vibration will damage the internal plates.

I use a pocket screwdriver to scratch the date in  the top of the battery along with the initials of my shop.

The new battery fully installed with the brace back in place.

All of my presets and memories are intact as well.

I chose an ACDelco 78PS battery with 700 cold cranking amps. This is due to my experience and the region of the country that I live in. The standard 78P battery has 550 CCA and that is not quite enough given the size of the engine (5.3 liter) and that we do have temps in the winter down into the low teens. The 78PG battery has 800 CCA and that is good for a much colder climate but it will not last very long with our long hot summers.

Now back to the customers’ vehicles.

2002 Ford F150, Battery Goes Dead Overnight

This 2002 Ford F150 came in with the complaint that the battery would go dead overnight. After the basics of checking the battery and alternator, I disconnected the negative battery cable and installed my Fluke multimeter in series between the negative battery post and the negative battery cable. I set the meter to read DC amps and adjusted the test leads accordingly. As you cane see in the next picture there was a sizable 2 amp draw on the system.

I turned my meter so that I could see it while working at the underhood fuse box on the driver’s side of the engine compartment. When I lifted the fuse box cover the drain went away. Since there is no switch that monitors the position of the fuse box cover, my educated guess was that a stuck relay just became unstuck. Not a good feeling because I do not know at this point if I could get it to stick again. Just for kick I closed the cover again and to my surprise the drain came back.

After opening and removing the cover, a simple visual inspection found the problem. The covers on the two larger square relays were not sitting level in the fuse box. I pushed down on the top of the two relays and found that the one on the left of the next picture to be the culprit. Pushing down on the cover made the drain occur and removing pressure from the cover made the drain disappear.

With the relay and cover fully removed for inspection, I thought I saw the problem.

However I was positive about it when I looked at the other damaged relay. Note the difference in the positions of the metal tabs at the top left corner of each relay. The tab on the left relay is bent out to a nearly horizontal position compared to the one on the right.

Two new relays installed and the 2 amp drain was gone. In case you are interested the upper relay in the next picture is the PCM relay and the lower relay is the fuel pump relay.

I find it unlikely that many of you will run into the same situation but I thought it might be interesting anyhow. The ironic thing about this vehicle is that there was a real .1 amp drain on the system after the relays wee replaced. My thought is that someone attempted to find this .1 amp drain and in the process caused the damage to the relays. The .1 amp drain was caused by a faulty add on electric brake controller. I located it by removing one fuse at a time in the fuse box above. Note the row of three pink, 30 amp PAL fuses. Removing the center fuse in that row made the .1 amp fuse disappear.

2001 Cadillac Deville, Driver’s Side Air Stuck, B0408

This 2001 Cadillac Deville came in with the complaint that the driver’s side vent temperature stays hot all of the time. I checked codes in the instrument panel module and found a code B0408 stored for a fault in the air mix one actuator. With the B0408 code the problem could have easily have been that the air was stuck on cold all of the time.

There are two 7 mm headed screws that have to be removed to take the under dash panel out.

Once the screws are out the panel will drop down and pull out from under the dash. Then grab the knee bolster cover along the lower edge and pull it towards the seat. Work up the sides  to the top. Pulling in the same manner to release the spring clips.

If you look above the firewall corner of the floor vent you can see part of the driver’s temperature or blend door actuator.

This picture was taken looking up from the gas pedal.

One of the screws that hold the actuator in place is directly above the floor vent duct work. I used a deep well 5.5 mm, 1/4″ drive socket and extension to remove that screw. The tip of the extension will come out to the rear of the brake pedal switches. Be careful to not move those two switches. If you do, your stoplights may not work properly and your transmission may not shift correctly.

The harness connector for this actuator only has two wires. A dark blue and a yellow wire.

The new actuator on the left and the old actuator on the right. The new actuator has the part number 89018380. The old actuator has a part number 52474878 on it. If you need one of these actuators please click here.

Accurate testing requires the use of a good scan tool and voltmeter but the actuator is almost always the culprit. If you want to do some testing, the a/c control panel will need to be removed. Start by gently prying down on the lower edge of the trim panel to release the clips. Once the clips are released start pulling the lower edge away from the dash and work your way up the sides. You will find the whole panel will seem to come loose except for the two top corners. Grab each corner as high as you can and pull straight out towards the seats. It may take a bit of pulling pressure to release the spring clips.

Now that the trim panel is removed, look closely at each side of the a/c control panel for the hold down latches. There are two on each side. Depress the latches and wiggle the a/c control panel from the dash.

A side view of the exposed latches.

After the control panel is removed you will notice that there are two harness connectors attached to the rear of the panel. The hook latches have to released by depressing the gray tabs at the wire side of the connector. With the hooks released, the connector bodies have to be wiggled/rocked and pulled to remove the harness connectors from the panel. Do not over flex as you could cause internal damage to the connector or the panel.

In the picture below I am pointing out the two wires that connect to the actuator, dark blue and yellow. Note that there are two yellow wires near next to the dark blue wire. One on either side. The correct yellow wire (B3) is the one one the left of the dark blue wire (B2).

The two wires at the actuator harness connector.If you feel the need or have other problems you can do a continuity test on the wires between the two connectors. Do not insert into the terminals that will distort them internally. These are micro 64 terminals and are easily damaged. Do your testing from the rear of the connectors.

As an added note. The control head applies 12 volt power on one wire and ground to the other for one direction of travel. It then reverses the polarity to change the direction of travel. When it has reached the desired position power (9.5-12 volts) is present on both wires and the actuator stalls  If a hard code is stored the new actuator may not work until the code is cleared. Clearing the code and actuator recalibration can be done with a scan tool or by removing power to the a/c control panel. This can be done by removing the HVAC BAT fuse in the rear fuse box. It is a 10 amp fuse. Make sure the ignition is off and leave the fuse out for no less than 60 seconds. Install the fuse, turn the ignition on and wait for two minutes. Do Not Touch Anything during this two minutes. Switch the ignition off and then back on. Check system operation.

The tools that I need to do this repair. A 1/4″ ratchet, extension, 7 mm and 5.5 mm deep well sockets. I also used a flash light and a 1/4 cordless driver.

This repair is a bit tedious but not hard at all.

2002 Chevrolet Suburban, Changing The Alternator

This 2002 Chevrolet Suburban came in with the battery light on and the system voltage at 12 volts. In talking with the customer, I found out that the battery light had been coming on and going off for a bout a week. Yesterday the battery went dead while driving. I was pretty sure just from this explanation that the alternator brushes were worn out. I performed a couple of routine checks and decided to pull the alternator for inspection. The first step would be to disconnect the battery negative cable and from there the intake tube needs to be removed. There is a hose clamp that has to be loosened at the MAF sensor.

There is also a hose clamp at the throttle body that needs to be loosened.

With both  ends of the tube assembly loose from the MAF sensor and the throttle body, there is one push pin fastener that has to be removed from the underside of the assembly.

Now using a wrench, ratchet and socket or the tool I am using the tensioner assembly needs to be rotated to relieve the tension on the belt. then the belt can be removed from the idler pulley and subsequently the alternator pulley.

Disconnect the harness from the voltage regulator by lifting the latch and pulling on the connector body.

Loosen the 10 mm nut and remove the cable from the alternator.

Loosen and remove the two mounting bolts. You will need to use a pry bar to rotate the alternator up and out of the mounting bracket.

Although I had not heard any bearing noises while the engine was running I always spin the alternator pulley and feel for any problems before replacing the brushes.

Before installing the repaired or replacement alternator, the slide bushings need to be squeezed back as shown below. They just need to move a 1/16″ to allow the alternator to drop back in the bracket easily.

All back together and charging like it should, as indicated by the voltmeter reading.

Replacing Worn Brushes In A Delphi Alternator

This alternator was removed from a 2002 Chevrolet Suburban. To replace the brushes in this alternator the rear plastic cover first has to be removed. There are several slots around the exterior surface of the black plastic cover.

Using a small screwdriver inserted into the slot, pry out on the lower end to release the hook. It helps to lift the plastic cover, either by hand or with another screwdriver, as the hooks are released.

With the cover removed there are three torx screws that need to be removed. One at the side of the brush holder assembly and the two that are on either side of the regulator plug housing. An E5 socket is needed.

All three torx screws are removed and now it is time to take the cap off of the brush holder assembly. There are two hooks on one side and one on the other. Care should be taken to only move the hooks far enough to release them as they can be broken easily.

The top brush is simple to remove as the terminal end will lift up and off of the regulator ear. Then the brush can be slid out of the holder slot. The lower one takes a little bit of effort. Gently lift up on the brush holder ear that is on top of the lower brush terminal end. A screwdriver works well for this. Then wiggle the brush terminal out from under the black brush holder ear. Once it is free the brush can be removed from the brush holder slot.

In the next picture you will see the new brushes to the right. I am holding the old brushes. Note that the surface of the brush on the right is shiny. It has been making contact with the slip ring on the rotor. The surface on the left brush is very dull and that is because it has had poor contact with the slip ring and arcing has occurred. The arcing causes the surface to dull and become slightly rough. You can click on the image to enlarge for a better view.

When installing the new brushes the longer side of the brush is inserted to the right side as shown below.

The brush has to be worked in a little at a time as shown below. It may require lifting the ear of the brush holder with a screw driver.

Once both brushes are installed I spend a little extra time to make sure the leads are fully inside the slots and the terminal ends are seated and square.

Normally when the brushes are correctly installed, they will hold in place long enough to place the retaining cap into position and lock it in place.

As you can see in the next picture there is quite a difference between the worn out brushes on the left and the new brushes on the right. If you need a set of brushes for your Delphi alternator please click here.

The alternator is charging again and for a much lower expense compared to buying an alternator.

You can also see it charging on the dash volt meter.

2002 Isuzu Rodeo, P0302

This 2002  Isuzu Rodeo with a 3.2 liter V6 engine came in with a flashing check engine light and a complaint of skipping. There was only a general misfire code P0300. I hate general misfire codes. I cleared the code and ran the vehicle under  load to induce the misfire. After a few minutes the light was back on and there was a code P0302 for a specific misfire on cylinder number 2. I removed the #2 coil assembly and this is what I found.  The spark plug boot and tube were heavily coated in soot.

The spark plug itself was a mess as well. The customer had installed new spark plugs about four months ago.

Before removing the spark plug I used a shop vacuum to remove as much soot as possible. Then a combination of wiping the tube with a rag wrapped around a screwdriver blade,vacuuming and blowing the hole out with an air hose. After I removed as much soot as possible, I removed the spark plug and started cleaning all over again.

In case you are wondering the number two cylinder is the front cylinder on the driver’s bank of the engine.

I had to remove build up from the coil tip as well. I used a wire brush and a rag to clean the coil.

Here are some of the tune up basics that I have learned over the years. Dielectric grease is good to put inside the spark plug boots but only a small amount. The amount on the tip of my screwdriver blade is about twice as much as is needed. I start with that much and make sure that about half of it comes back out after spreading a light film inside the boot. The dielectric grease is used to make sure the boot slide on and off of the spark plug with reduced effort. Too much grease and the spark will cut a carbon track down the side of the plug. This will result in a misfire and the need for more parts.

The two most important things I use in spark plug replacement are a spark plug gap checker and a torque wrench. Not all spark plugs arrive properly gapped and improper torquing of the spark plug will result in a loose spark plug as wee had in this repair article or damaged threads in the cylinder head. Because of space problems a torque wrench cannot be used for every spark plug. Doing as many as possible, on a particular vehicle, will give you a feel of what the correct torque is though. The correct torque on this vehicle was 18 ft lbs. This torque is needed to compress the crush gasket on the spark plug. This gasket provides the seal against combustion gasses.

2006 GMC Yukon, P0449

This 2006 GMC Yukon came in with the Service Engine Soon (SES) light on and a code P0449 stored in the PCM memory.

This test should be done on the vehicle but I could not figure a way to o the test and position everything for a good picture. So you will just have to imagine this is still in the vehicle. Connect an ohm meter across the two solenoid terminals and measure the resistance. This one is open so I know it is bad.

In further testing there should be battery voltage on the orange wire, terminal “B” at the red harness connector. The PCM applies a ground to the white wire, terminal “A”when operational conditions have been met. The Canister Vent Solenoid Valve is located at the rear of the fuel tank as shown below. Be careful when working with these parts. As they age they will become brittle and may not be replaceable. This of course refers to the hose and electrical connector.

To remove the hose the two ends have to be squeezed together in order to release the locking tabs. I find it easier to slide a small pocket screwdriver into the hose fitting to release the locking tabs.

Once the tabs are released the hose has to be pulled and rotated to remove it from the solenoid assembly.

The electrical connector is located on the left or driver’s side of the solenoid.

It has a thumb latch that has to be lifted while the connector is pulled away from the solenoid.

There is a metal locking tab on the mounting bracket that will bend out easily as shown below.

Then the solenoid can be slid back and off of the bracket.

The new canister vent solenoid valve installed.

I cleared the code with my Tech 2 scan tool and switched the ignition on and back off several times to allow the PCM to do it’s self tests of the solenoid. It passed and this one is done.

2003 Nissan Maxima, Power Window Calibration

This 2003 Nissan Maxima came in with the complaint that the passenger front window would go down on it’s own. What I determined was that when the window was raised up, it would automatically cycle down about six inches. If the glass, motor or regulator have been removed a relearn procedure is needed to restore proper operation.

The first step in this process it to remove the door panel. If you have already removed any of the listed parts you of course already know how to remove the door panel. Lift the screws cover in the door panel pull handle.

Then using a philip’s head screwdriver remove the single screw.

Lift and remove the switch trim panel.

There are retainers at both ends that have to be dealt with.

Remove the outer trim ring from the inside door handle.

You have to work along the inside edge of the ring to release the locking tabs.

Remove the screw cover at the front of the door panel.

Then the phillip’s headed screw.

I am pointing to the rest button on the power window motor.

To reset the upper and lower limits:

Make sure all switches are connected.

Turn the ignition switch on.

Raise the window fully. You may have to play with it to get it to stop at the full closed position.

Press and hold the reset switch.

While lowering the window fully. I am holding the switch with my unseen fingers. Kind of hard to hold the reset button, lower the window and take the picture all at the same time.

Release the reset switch. Make sure it pops back out.

Raise the window fully.

The limit switches are now reset.

Now the most important part of this procedure. If the door panel is already back on, the procedure can be done by only removing the switch cover and locating the reset switch button that I am pointing to with my screw driver. If you cannot reach the reset button with your fingers you should be able to with a large tipped common screwdriver.

2005 Buick Lesabre, Changing The Gauge Stepper Motors

The gauge stepper motors had failed in this cluster. If you need to see how to remove the instrument cluster please click here.

The first step was to remove the four screws and lever latches that hold the instrument cluster to the dash carrier.

Then using a small screw driver to release the clips that hold the black face assembly to the white housing, I worked my way around the instrument cluster until it was loose. Be careful to not touch the inside surfaces of the lens assembly. It will leave finger prints and disturb any dust that may be present. Unless you just want to fully clean it.

Do Not remove the rear black cover yet. Place your finger in the gauge needles and turn them lightly counter clockwise.

Until they stop.

Using an easily removable masking tape, mark the full CCW position of all of the needles.

Now turn the needles past the stop to loosen them on the motor shafts. Press closer to the center than at the tip to avoid damaging the needles.

Using a dinner fork that will clear the center section  of the needle shaft, pull the needles up and off of the motor shafts. I try to practice pulling straight up. Even if I have to grab the handle and the tines of the fork. This skill will come in handy if the needle has to come back off without damaging the new stepper motors. Sometimes you miss when installing the needles and sometimes something goes wrong. I repairing this particular cluster, two of the new stepper motors were no good. I had to replace them a second time.

All of the needle positions are marked and the needles removed.

Now the clips that hold the back cover in place can be unlocked and the cover removed. It is very important to not remove this cover until all of the needles have been marked and removed. If you were to remove this panel first the needles could be off as much as a quarter of an inch. Ask me how I know.

This is what the inner circuit board looks like. The round white pieces are the stepper motors.

There are four soldered leads at the back of each of the motors. I use a 25 watt soldering iron to do this job. The leads will come loose without much trouble but the plastic pegs seem to be tight in the circuit board sometimes. I find it best to hold the white part of the motor with the finger tips of one hand, while I apply heat to the terminals in an alternating fashion. I use the finger tips of the one hand to apply pressure between the motor housing and the circuit board. Sometimes I have to use a small screwdriver as a lever to pull the motor loose. Do not use too much pressure or apply the pressure before the solder is fully melted or you may pull part of the circuit board through the hole with the lead. Also do not rake the melted solder to try and open the hole. You will damage the circuit board. Either use a solder sucker of some sort or at least use a small piece of wire to insert into the melted solder to open the hole up.

I did not show any pictures of the actual soldering. I believe that if you do not already have some quality soldering experience you should not do this part of this repair. Instead enlist the help of someone who does.

Be careful to not touch the other electronics on the board. It is best to ground yourself so that will will not conduct a static charge that may damage the electronics of the instrument cluster.