2001 Ford Expedition, Testing The EGR Valve

This 2001 Ford Expedition came in and the customer requested that the EGR valve be changed. I asked why and was told the parts store checked it and it had a code P0401 for insufficient EGR flow. I said okay, but I was willing to bet  that the EGR valve was okay. The customer asked why I was so sure and I informed him that I have repaired a code P0401 in many different Ford vehicles, hundreds of times and I have never changed an EGR valve to fix this code. I am not saying that the EGR valves cannot fail but I personally have not seen it be the cause of an insufficient egr flow code. I told him it would take about five minutes to test the valve. First I went and got my hand vacuum pump, as pictured below.

I located the ERG valve on the driver’s side of the engine.

I disconnected the vacuum hose.

With the engine idling I hooked up my hand vacuum pump and applied about 25″ of vacuum to the EGR valve.  The engine idle surged down almost to a stall condition and then recovered and ran a little rough. The valve held vacuum and the engine almost stalled so the valve is good and the passages are open. We need to look for something else and not waste money on replacing a good EGR valve.

If the valve would not have held vacuum the valve would have been faulty. If it would have held a vacuum and the idle speed changed very little or not at all, the valve would most likely have been okay and the egr passages would have been blocked with carbon build up. Another thing to keep in mind is that if no change in engine rpm is noted, the engine should be turned off and then apply vacuum to the EGR valve again. Movement of the pintle and the diaphragm should be heard and felt, while applying vacuum and during quick release of the applied vacuum. . If vacuum is held and no movement is detected the EGR valve itself may be stuck. The customer paid the bill and said he would be back but I have not seen him yet. This one or another one will come in soon and I will document what really is the problem.

1997 Chevrolet K1500, Turn Signal Problems

This 1997 Chevrolet K1500 Pickup came in with the complaint of the left turn signal will not work with the headlights on. I checked and the turn signals did work with the headlight off but the actual problem was that the turn signal would not work with the park lights. In fact if the park lights were turned on the left turn signal indicator light in the dash would come on and stay on. From experience I thought the problem would be in the left front light assembly and possibly a bad ground or a shorted bulb. I removed the screws that held the light in place.

Then I removed the sockets from the light assembly. The bulbs looked okay but I went ahead and pulled the bulbs out. The bulbs were not damaged. But I did see something strange in one of the sockets.

It was the solder from an old bulb that had come out and gotten stuck between the two terminals in the socket creating a short between the park and turn signal light circuits. Another one fixed.

1998 Chevrolet Lumina, Battery Goes Dead

This 1998 Chevrolet Lumina came in with the complaint that the battery will go dead after about 2 days of sitting. I checked and sure enough there was a .5 amp drain on the system. I had also noticed while moving the car around and locking the car up for the night that the power door lock switch on the driver’s door had problems. The spring tension that keeps the switch centered during non use was gone and the switch could basically flip back and forth. I removed the single screw holding the switch panel in place.

Pulled the panel away from the door.

Released the front spring clip.

Unhooked the wiring harness connector and the drain was gone.

Removed the old switch by gently lifting the retaining tabs as shown below. Installed the new switch in the panel.

Installed the panel on the door and this one is done.

2001 Dodge Durango, ASD Relay Fuse Blows

This 2001 Doge Durango with a 4.7 liter V8 was sent to me from another shop. The truck had come to them with a head gasket leak, which they had already fixed. A new problem had developed though in that the ASD relay fuse in the under hood fuse box would blow sometimes and the engine did not run great. The other shop said that they had checked all of their work and could find no place where they might have shorted out any wiring. To do my job I of course had to go back through every thing that might have been checked. I started by removing the blown 30 amp ASD relay fuse.

I installed a 30 amp circuit breaker in its place and tested the amp load on the circuit by hooking the inductive amp clamp from my tester around one of the jumper wires. I turned the key on and nothing unusual. I cranked the engine and the engine fired up and ran okay but not real good. I monitored amp draw while running and everything seemed okay until the idle speed came down below 1500 rpms. The amps jumped up to about 25 amps, so I gave it a little gas to get the rpms up again and the amps started spiking to 60 + amps. They came back down after getting over 2000 rpms. This was about the strangest thing I had ever seen.

I shut the engine off and checked all of the basic wiring around the injectors and coils. All seemed okay. I checked the diagrams and found that the fuse shown below would eliminate the O2 sensor heaters so I removed it. I found an ignition capacitor on the passenger inner fender and disconnected it. I retested and the same thing happened again.

What in the world could it be? I decided to start checking the coils for amperage draw individually. Hopefully I would find a shorted coil. I removed the tape and separated the wires.

I hooked the inductive amp clamp around one of the wires. It did not matter which one.

I cranked the engine and monitored the amperage draw.

Well I’ll be, 8 amps times 8 cylinders equals 64 amps. That definitely could blow the fuse and could be the explanation of the intermittent high amp draw. Most of the cylinders could be firing at the same time, although they should not be unless the base timing is off. How could the base timing be off there is no distributor and none of the sensors are adjustable? Son of a gun, the timing chains could be off a tooth or two and that could explain the dwell overlap. Yep, engine is an overhead cam design and the chains had to be taken loose to change the head gaskets that were leaking. I have never seen a mechanical adjustment cause an electrical overload on a vehicle before. Now I have!

I called the other shop and broke the bad news to them. They picked the truck up and reset the timing chains and all it well.

1998 Pontiac Grand AM GT, P0171

This 1998 Pontiac Grand Am Gt with a 3.1 Liter V6 came in with a surging idle and service engine soon light on. I checked codes and found a code P0171 stored for Fuel Trim System Lean. Sounds like a vacuum leak to me. I tested with propane and found that by adding fuel near the pcv valve hose tee, at the throttle body, that the idle would smooth out.

I removed the two top screws for the throttle cable bracket.

Then loosened the hose clamps and removed the intake flex tube.

Now I could access the lower nut that was still holding the bracket in place.

I then went to the rear of the engine and removed the harness connector shown below so that I could gain access to the other end of the tube assembly.

I installed the new tube after cleaning the goo (technical term) out of the hole in the throttle body. Connected the hose at the rear of the engine, installed the pcv valve and installed all previously removed items.

I think you can see the difference between the grommet on the old hose tee and the new one.

2005 Chevrolet Impala Battery Goes Dead

This 2005 Chevrolet Impala came in due to a battery drain condition. I checked and sure enough the was a 2.25 amp drain on the system at all times. In researching I found something interesting about the Tech 2 and monitoring sleep and wake modes. I hooked the Tech 2 up and went into the class 2 message monitor to view the module state (active or inactive). This can be done with the key off and of course active means awake and drawing current and inactive means asleep and not drawing current. The interesting thing is the the number value after the status of the module also indicates sleep (even number) or awake (odd number) and it is cumulative.  In that a higher number indicates that the module has gone to sleep  and woke back up many times. A value of 15 would mean that the module has gone through the awake/sleep cycle 7 times and is currently back awake. The instrument cluster had the highest value at 137  after about fifteen minutes. Other modules also had high numbers but the instrument cluster was the highest. I disconnected the cluster and reset the monitor and all other modules went to sleep in less than two minutes. A new cluster and this car was fixed. I know this will probably only help some one that has a good scan tool but if you determine that you have a 2.00 – 2.50 amp draw, it may be worthwhile to disconnect the instrument cluster to see if the drain goes away.

2001 Saturn SL Blown Bulbs In Instrument Cluster

The customer came in with this 2001 Saturn SL and a couple of bulbs she wanted replaced in the instrument cluster.  One for the DRL indicator (daytime running lights) and the other for the odometer. The first step was to remove  the covers from the steering column. There were five screws with 5.5 mm hex heads.

Next I removed the two 7 mm hex headed screws at the driver’s side of the dash.

With the screws removed I could pull the end panel off.

Next, I pulled the cluster trim panel from the dash and unhooked the wiring for the switches.

A better view of the panel with the traction control switch and the panel dimming switch.

I removed the two screws at the top outside corners of the instrument cluster. Then, lifted and pulled it forward enough to reach behind and remove the harness connector.

The bulbs can be changed with the cardboard panel in place but I removed it to see if there was any identification marks on the circuit board.

There were none so I had to remove several to find the one for the DRL. It is the one in the next picture.

I then needed to change the bulb for the odometer backlighting. It is the one with the white base.

A 6 mm socket fits the bulb bases by the way.

This is the bulb for the odometer. It is actually a LED.

Performed a bulb check to make sure all bulbs would light up and this one is done.

2003 Toyota Highlander, A/C Stuck On Heat, Part 1

This 2003 Toyota Highlander came in with the complaint that the a/c only puts out hot air. I confirmed the complaint and removed the glove box to access the air mix actuator assembly.

I had to push the hinge pins out to remove the glove box.

I then had to remove the screw and bracket that hold the cable.

With the glove box out of the way, I had to remove one screw and release some retaining clips in order to remove the white duct assembly.

I checked the feed back sensor (orange wire) and it was reading about .8 volts at the full heat position. I started moving the temperature knob while watching the voltage and I noticed that the actuator arm would occasionally move and the sensor value would change. I found a sweet spot and the actuator would move to almost full cold. Looks like I need to go to the control assembly.

I first wanted to check the switch and knob to make sure nothing was stripped and after pulling the knob off I found that the switch was loose in the control assembly. I tightened the nut and the system now works properly.

I would assume that the actual switch mount is one of the control circuits and it could not make proper contact with the nut loose. Well, this turns out to only be a diagnostic aid. I will have to go deeper into the control head as soon as the customer can leave the vehicle again. I checked on the price of a new a/c control assembly. Almost $700 from the dealer and the only service part is the blower switch. This one is okay.

I have fixed this one and I will be giving an updated post in a few days. Pretty delicate work but it saved a $700 control assembly. Click here for updated repair.

2000 Ford Expedition No Run Condition

This 2000 Ford Expedition was towed in due to a no run condition. I checked for codes and found that I had no communication to the Powertrain Control Module or the Instrument Panel  Cluster. I also noted that the odometer was displaying dashes.

I decided to start checking power at the PCM relay. It is the square relay in the upper left corner of the following picture.

I removed the relay and checked for power input at terminal #30. Power was present.

I jumpered terminals #30 and #87  together  and checked to see what I had. The dashes in the odometer display turned back to numbers. Jumping out relay terminals is a very exacting procedure and if done incorrectly the computer control unit (PCM) can easily be damaged. I now had data for the PCM and The IPC. The engine would now crank and run but it would shut off after a few seconds. I checked and cleared all codes and now the the engine would crank and run normally.

I also went ahead and changed the fuel pump relay as a preventative maintenance service. It is the square relay in the bottom center of the following picture.

2002 Honda Accord A/C Controls Inop

This 2002 Honda Accord came in with the complaint that the blower worked but nothing else on the a/c control assembly worked or would even light up. I started by checking the #3 fuse in the driver’s side interior fuse box (7.5 amp) and the #13 fuse in the passenger side interior fuse box (7.5 amp). Both fuses were good. Time to remove the a/c control assembly for testing of the harness. First I removed the two lower retaining screws.

Then I used a small screwdriver to pop the clock and hazard switch assembly from the dash.

With the panel removed I could now access the one hidden screw and pulled the panel with the a/c control assembly out of the dash.

I then removed the control assembly from the panel.

Then reconnected it to the wiring for testing.

I had to disconnect the control assembly to get better pictures of the wires. First I checked for ignition power on the black/yellow wire at position 2. Good

Then I checked for battery power on the white/yellow at position 3. Good

Then I checked for continuous ground on the black wire at position 9. Good

DSC01561

Diagnosis and replacement of faulty a/c control assembly.