Page 3 – Sparky's Answers

2012 Cadillac SRX- Headlight Keeps Burning Out

This 2012 Cadillac SRX came in with the complaint that the passenger side low beam headlight keeps burning out. The customer had the halogen bulb replaced several times before bringing it to me. In order to get a good look at what was going on the air filter housing assembly had to be removed. Disconnecting the MAF sensor and removing the harness from the top cover was the first order of business. Next the hose clamp had to be loosened and the hold down clamps had to be released.

After the top half of the air filter housing was out of the way the bottom needed to come out. It is quite a chore to lift it off of the mounting pegs and then wiggle and twist it around just right to get it out of the hole. You may be able to work around not removing this or possibly not completely removing it but I need the extra room to work and take pictures.

The cover at the rear of the headlamp assembly turns to the left and then will pull off of the headlamp assembly. Once the cover is off the bulb and harness are turned as an assemebly and removed from the lamp.

Then the connector can be removed from the bulb. Enlarging the next picture will allow you to see how badly the connector is burnt. Unfortunately the bulb was replaced several times but none of the installers bothered to replace the harness connector.

I installed a new harness connector using splicing terminals and heat shrink tubing.

The wires spliced in and the heatshrink tubing in place.

To install the bulb and connector they should be connected to each other and then installed into the lamp assembly as a combined unit. Making sure to not touch the glass portion of the bulb. Always install a new bulb when replacing the connector or the repair will not last very long. Heat damage transfers.

2004 Dodge Durango-Blower Not Working

This 2004 Dodge Durango came in with the complaint that the blower did not work sometimes. Of course now that it is 95°F the blower hardly worked at all anymore.

A burnt terminal at the blower motor resistor ….

…. and the blower resistor harness connector is a very common problem on these vehicles. The blower resistor is located behind the glove box area and can be accessed under the edge of the dash. Two 5/16″ or 8 mm headed screws hold it in place. I used a boxed end ratcheting wrench to remove them. The red secondary lock on the top edge of the connector has to be slid towards the right before the thumb latch can be depressed and the connector removed.

I have a twist on this repair that will help prevent this from re occurring. Note the crossbar between the two vertical bars on the right hand side of the resistor.

This crossbar bypasses the high blower circuit around the resistors and connects it directly to the blower motor lead. The trouble is that regardless of the commanded speed the far right vertical bar is always feeding the blower motor.

What I do is make that connection in the wiring on the outside of the resistor. This now directs the high blower command away from the inside of the resistor and creates two output legs to the blower motor for the lower three speeds. Also the high blower will now work with the blower resistor disconnected from the circuit. The two factory wires that are joined together are both dark blue with a gray stripe. I used a 10-12 gauge splice terminal and the appropriate sized heat shrink tubing to connect the four wires together. The two factory wires were a tight fit and it took some patience to get all of the strands lined up and inserted into the terminal. The rest were 14-16 gauge terminals and heat shrink tubing. I prefer using seamless non insulated terminals with a heavy side wall. They cost a few cents more but cheap parts make for a cheap repair that will not hold up.

The new harness connector spliced in and taped up. If you reach up behind the glove box area you can remove the part of the harness that is secured by a hook on the blower case. Doing so allows much more room to work on the harness.

A look and the new resistor and harness connector installed behind the glove box area.

2006 Buick Lucerne-Runs Hot

This 2006 Buick Lucerne came in with the complaint that the engine would run hot sometimes. The cooling fans had been replaced with used parts and the coolant reservoir had also been replaced. The customer had stated that someone told them that the oxygen sensor could be causing the problem. I told him that I doubted that but would look into it. Well it turns out that a blown oxygen sensor heater fuse can cause an overheating issue.

The fuse is labeled as OXY POST and it is at position F21.

There had been a 25 amp fuse installed and it was blown. I replaced it twice and the new fuse would blow as soon as the ignition was turned on. As luck would have it though on the third try it stopped blowing and the short was gone.

I looked at a common area where the wiring is known to short out on theses vehicles but no short was found. This harness runs along the front of the engine just below the upper radiator hose.

It took quite a while to locate the short by my diligence paid off. The short was located where the rear wiring harness turns down and goes behind a power steering line. It was rubbing on the hold down clamp that secures the line to the engine.

I had to disconnect the wiring harness from the rear oxygen sensor, the transmission output speed sensor and the right front wheel speed sensor. Disconnecting the rear oxygen sensor involved drilling out three rivets that held on a heat shield over the wiring. Finally the harness was up where it could be repaired.

A close up of the damaged pink/black wire.

The removed degraded split loom and harness tape.

The cleaned up harness with new split loom and heat resistant tape. Nothing like being wrapped up under and around a vehicle, working through a wheel well and other minor openings for a whole day fixing a tee tiny little short.

The really fun part was re installing the harness and routing it correctly. By the way even though the old split loom was degraded and left the wiring exposed for damage the real culprit in this problem was whoever had replaced the rack and pinion assembly had left it’s heat shield loose. The wiring harness is secured to the heat shield and was being moved around while the vehicle was being driven. Including gravity pulling down and causing the wire to cut into the metal hold down clamp. In nut shell old parts and poor workmanship caused this problem. Now they just have to fix a half dozen or so other issues and the vehicle may be dependable.

2008 Chevrolet Cobalt-Blower Not Working

This 2008 Chevrolet Cobalt Came in with the complaint that the blower did not work. Customer also stated that they had been smelling something “hot” for a “little while”.

Removing the HVAC control panel is fairly easy.

Open the glove box and pull the right trim piece off of the dash. You may need something to pry with.

Remove the short trim panel to the left. It is a little more difficult to remove due to the lack of leverage.

The lower edge is tucked in behind the knee bolster trim panel and will need a little extra work to maneuver it out.

Now the main trim panel can be removed. It also pulls out.

There is a harness that is connected to the back of the panel. It would be optional to disconnect it or not but I find it easier to work with it out of the way.

Two screws with 7 mm heads need to be removed.

I would imagine this is the “Hot Smell” that the driver had noticed.

The two undamaged connectors were removed with no problem. Just depress the thumb latches and pull.

The blower switch was a different story though. I removed the two T 10 screws that held the switch in place and wiggled and pulled the switch from the HVAC panel.

I was also pulling the blower switch knob in the opposite direction at the same time.

With the switch removed from the HVAC control panel I could pry, pull and twist to my hearts content without fear of damaging anything else.

I started splicing in the replacement harness connector one wire at a time.

Staggering the splices make for a neater repair.

Next I heated the heat shrink tubing over the splice joints and wrapped the harness with tape.

In the process of installing the switch into the HVAC panel I noticed something rattling around. I unclipped the black front cover from the white rear housing. The part numbers on the assembly are 15890411 and 28043865.

I then lifted the light projecting panel from the face plate….

… and found this terminal from the old blower switch.

Nothing was found in the rear housing.

I decided to check the back lighting operation before reassembling the control panel. The lower right bulb was not working.

I soldered in a new bulb and rechecked.

After putting everything back together and checking the blower operation. All was well.

A few things to discuss.

in the next image you can see the original Delphi part number of the switch is 28026213.

The switch is actually a five speed switch but the stops on the knob only allow it to function on the first four speeds.

The switch is not listed by GM or ACDelco by application.

It is available here with the repair harness.

If you want the bulbs too you would need this kit.

2008 Ford Expedition-Power Seat Not Working

This 2008 Ford Expedition came in with the power seat not working. testing found that fuse number 45 in the underhood fuse box was blown.

The problem was intermittent so I installed a new fuse and marked it’s location on the fuse box cover. The customer was on her way out of town so there was not enough time to locate and repair the problem.

When the customer returned a few weeks later and dropped the vehicle off I started searching through wiring diagrams and inspecting the vehicle. This vehicle has a power seat system that is referred to as 10 way with memory. Because of this most of the functions go through the Driver’s Seat Module (DSM). The problem that this causes is that the driver’s power seat, the adjustable pedal system and the power mirrors all integrate with the DSM. Service information nor wiring diagrams do not specify which of those circuits may or may not be integrated into the fuse #45 circuitry. The mirrors were easy enough to take out of the equation since they worked with fuse number 45 removed. I pulled the knees bolster panels under the steering column and inspected the wiring harness routing for signs of rubbing and found none. I then pulled the driver’s seat out of the vehicle and inspected the wiring. It was quite difficult to find but after doing so I realized it could have been located and repaired without pulling the seat. The front panel of the seat (not shown) unsnaps from the seat by pulling it straight out. Then there is one screw on the front corner of the side panel that needs to be removed before the side switch panel can be removed.

With the switch panel out of the way the inner support bracket can now be removed. There are several phillips headed screws that hold that panel on. There are also a couple of slide/slot holders at the lower edge that require sliding the bracket to remove it.

Unfortunately I had already located, repaired and secured the damaged wiring before I had gotten around to thinking about documenting this repair. The area that I am pointing to in the next picture with both my finger and a screwdriver is a plastic trough that the wires are supposed to be resting in. Well since I am discussing this they were not secured in this location. Instead they were hanging down ….

… and would occasionally rub against this bracket. The signs of rubbing were barely visible and I had to use a magnifying glass, bright flashlight and careful inspection to be sure I had found the spot.

The wire that was shorting out was purple with and orange tracer and supplies power to the back rest recliner.

I wrapped tape around the wound on the purple/orange wire to seal it and then carefully wrapped the trough with electrical tape to keep the wires secured inside the trough.

2003 Chevrolet Express Van-No Crank Condition

This 2003 Chevrolet Express 2500 van with the 5.3 liter engine was towed into my shop as a no crank condition (starter does not work). There were two problems found. The IGN A fuse was blown in the underhood fuse box and the starter was no good. The starter had been replaced the day before by the owner but during installation the solenoid cap was allowed to rotate and it broke the “S” terminal wire internally. The rotation problem was a combination of a poor quality replacement part and lack of experience of the installer. An improvement in either could have prevented that problem.

The owner informed me that the IGN A fuse had been blowing sporadically for a few weeks. Although I could not duplicate the IGN A fuse blowing I took the customer at his word and started going over the wiring diagrams and inspecting the vehicle for problems. I spotted a potential problem area during my inspection and accessed the wiring harness through the passenger front wheel well. The split loom had started falling apart from where it had been ….

… laying on an air conditioning hose.

Inspecting the back side of the wires with a mirror found the spot on the purple wire that had been hitting the a/c line.

You can see the wear in the metal fitting where the corrugated loom had been rubbing on it for a long time.

A little bit of electrical tape and new new loom and this problem was fixed.

2011 Chevrolet Impala-Fuel Pump Not Working

This 2011 Chevrolet Impala came in after the fuel pump and fuel pump relay had been replaced and there was still no fuel pressure. I was told by the customer that the computer must be bad and it was brought to me because programming would be needed. Proper testing could have prevented replacing parts that were good.

In the next picture I am pointing to the fuel pump fuse. The simple test is to check for voltage on this fuse while cranking the engine. If nominal battery voltage is present the computer system, relay and wiring harness to this point are all good. The PCM energizes the relay and the relay in turn sends out power to the fuel pump fuse. The fuse supplies power to the fuel pump.

The fuel pump relay is directly below the fuel pump fuse.

Since I knew the above portion of the fuel pump control circuit was okay I looked to see what might be in between the fuse and the fuel pump. There was an inline harness connector listed and identified a X200. It is located behind the passenger kick panel. If you enlarge the next image you should be able to see an arc mark on the third terminal from the left on the top row.

On the mating connector you can clearly see the discolored plastic at the same location.

Before separating the connector I tested for voltage at the large gray wire at that location. No voltage was present while cranking the engine. To repair the condition I cut the gray wire out of both connectors and spliced them together with about an eight inch piece of 12 gauge wire.

2005 Ford Escape-Reduced Air Flow From A/C Vents

This 2005 Ford Escape came in with the complaint that the air flow stopped coming out the vents sometimes. The owner said he did not feel it coming out anywhere else either but he also had not checked real well either. I inspected the vacuum hoses, check valve and reservoir under the hood and found no problems. Normally the airflow will shift to the defrost if there is a vacuum problem. I test drove the vehicle a couple of different times and on the last test drive the problem occurred. The air flow was very reduced and it was not coming out of any other vents. Pretty sure I know what’s going on now. I lifted the hood and saw a significant frost build up on the a/c lines.

The compressor was engaged and the engine was running during this test. The reduced air flow was being caused by the same frost buildup on the evaporator core. Effectively turning it into a block of ice that air could not pass through. I disconnected the clutch cycling switch and the compressor immediately disengaged.

I left the switch disconnected and allowed the engine to continue to run.

Slowly the frost melted…

…and the airflow was restored. I installed a new clutch cycling switch and test drove again to complete the repair.

Had the compressor stayed engaged after the switch was disconnected I would have looked further to see if the relay was sticking or if there was a mechanical clearance issue at the compressor clutch. One last note about this repair. I did notice that the compressor and the accumulator had recently been replaced. This faulty switch could have easily lead to the original compressor failure and certainly would have caused the replacement compressor to fail if I had not found the issue.

2009 Chevrolet Silverado – Poor Heat If Temperature Set Below 90°F

This 2009 Chevrolet Silverado came in with the complaint that the heater was only mildly hot unless the temperature was set to 90°F. When set to 90° the heat worked very well. I should point out that this truck has automatic HVAC controls as evidenced by the word “Auto” on the control head assembly. I also want to let you know that this symptom generally applies to most GM vehicles built after the 2000 year model with automatic temperature controls.

I had already looked at data and saw that the interior temperature sensor was reading higher than it should by 10° to 15° Fahrenheit. The interior temperature sensor is located above the driver’s head and contrary to popular belief it is not a speaker or a microphone for the OnStar system. It is a very neat little sensor but it is actually much more than just a sensor. It has a built in fan that draws air in from the passenger compartment. The created air flow forces cabin air across the thermistor and with the use of various electronics converts that information into a temperature value that the HVAC module uses to adjust the temperature door actuators. If the temperature reading is too high the system will keep the cabin cooler than desired because it is trying to lower that false high temperature.

The chief cause of failure of these sensors is dirt/dust and I will show more of this later. GM service information states to disable the SRS system, remove the front and rear sill plates, remove the lower center garnish molding and then finally the upper center garnish molding. I prefer to save time and only loosen the upper panel. First the screw cover panel has to be removed.

Then one screw with a 7 mm head has to be removed from the forward hole. The panel can now be pulled towards the center of the vehicle a couple of inches.

The driver’s sun visor needs to be removed from the vehicle. Start by grasping the cover panel at the outer edges and working it free from the base.

There are three T15 torx screws that hold the visor assembly to the roof of the truck.

Pay attention to how the wires and harness pull out of the headliner. You will need to remember this for re assembly later.

Next the “A” pillar trim panel has to be removed. First the screw cover panel.

Then the 7 mm screw. If there is a pull handle installed at this location it will need to be removed and there will be another screw at the other end.

With the screw removed the upper edge can be pulled down to release the retainers. Then the entire panel will be lifted up and off of it’s resting place on the dash cover.

The door weatherstrip can be pull down and off of the metal lip.

Now I carefully pull down on the headliner assembly and use my flashlight as a wedge to hold it down slightly. Again I said carefully because the headliner can be damaged if over flexed.

I use long needle nose pliers to grip the harness and a long flat blade screw driver to lift the locking tab on the sensor. I could not hold both tools and the camera all at the same time so you will need to use your imagination here.

Since I know I am going to install a new sensor assembly I am not concerned about “saving” the old one. In fact I intend to break it. Using a couple of long flat blade screw driver’s I flex and pry the sensor away from the headliner.

There are a couple of latches that can be pushed in so that the rear/upper housing can be freed from the base plate. Sometimes the housing breaks and sometimes it comes off in one piece. Again I am installing a new one so I do not care if the sensor breaks.

The only things that I do not want damage are the headliner and the inner grill/cover.

The view with the grill removed. Note the four slots around the outer edge. The grill’s locking tabs snap into these slots and are quite difficult to remove without breaking or damaging the headliner surface. That is why I remove the sensor in pieces. With the upper housing assembly removed you can access the retainers from the top side and push them over so they can be released without damage to the grill.

The interior sensor fully removed.

The new sensor assembly to the left and the old sensor base plate and grill cover to the right.

In the next image you can clearly see what is wrong with the sensor assembly. A heavy dust build up on the fan blade reduces the air flow volume and the dust build up on the thermistor insulates it from the incoming air and keeps the temperature reading high than it should be.

I know your first thought is why not just us an air hose and blow the dust off without removing the sensor? Notice that there is nothing between the thermistor and the fan blade on the original sensor. Blowing enough air into the sensor to clear the dust would also blow the thermistor into the fan blade.

The replacement sensor is assembled differently and blowing it clean would work better.

1996 Ford F150 – High Idle in Park & Neutral

Will G: I have a 96 Ford F150 with a 5.0 liter engine and in park or neutral the idle wants to climb to almost 2000 rpm. I took a look at the throttle plates and they are nasty/heavy carbon looking. When in Drive/Reverse idle is around 700 rpm or so. I’m guessing dirty throttle body and/or IAC?

Sparky: Anything is possible but normally dirty throttle bodies and throttle plates result in a low idle. My thoughts would be a vacuum leak, sticking IAC (tapping on it will sometimes break it free) or erroneous data that is causing the computer to command a higher idle.

Will G: I went ahead and cleaned the throttle body and IAC with no luck. Blocked the IAC by putting a piece of soda can between the IAC and throttle body. It would barely run which to me indicates no vacuum leaks after the TB. Removed the piece of soda can and the high idle is still there. It was running fine the other day.

Sparky: Disconnect the two wire harness to the IAC and see if the idle drops. If it does the computer is commanding it open and further diagnosis is needed. If it does not drop the IAC is stuck and needs to be replaced.

Will G: Ruled out IAC by unplugging IAC while running and the idle will slow down and it will die. Throttle plates are fully shut by visual inspection. When I first bought the truck last year it was throwing bank 1 and 2 too lean which was a combination of exhaust leaks and dirty MAF. Local garage smoked intake for vacuum leaks and checked fuel pressure. No vacuum leaks and fuel pressure was OK. Garage repaired exhaust leaks and cleaned MAF. No CEL and no driveability issues other than the high idle when in Park and Neutral. Borrowed an OTC Genisys scan tool and verified that the ECT and IAT sensors are reading properly. My thought is a faulty TPS as the TPS mode reads PT and not closed when it’s at dead idle.

Sparky: It would seem you are on the right track. If it were in my shop I would connect a sensor simulator to confirm the diagnosis. Check to make sure there is no play in the throttle shaft that could account for the slightly high voltage and the PT reading. Also check the base idle screw to make sure it has not been adjusted. If nothing is found try doing a KAM reset with the scan tool and see what happens. Also wanted you to confirm how many pictures you uploaded.

Will G: The throttle shaft is tight. I have not messed with the base idle screw and it is tight. I uploaded 2 pictures. I’ll throw the scan tool on it before I head over to my buddies place tomorrow and monitor the ECT IAT and fuel trims.

Will G: Went over to my buddy’s and we checked for vacuum leaks and found none, O2 sensors are switching and it is going into closed loop. Reset the KAM and still idling high. At idle the TPS reads 20% and the factory spec at idle is 0-15% which confirms my suspicion of a faulty TPS.

Will G: I have ordered a new Motorcraft sensor, throttle body gasket, and throttle body coolant hoses. I’ll let you know how I make out. Getting back together with my buddy next Sunday to replace the sensor and confirm the repair.

Will G: Got together today with my buddy and we replaced the TPS and all is well. Hooked up his Snap On Ethos and the TPS voltage at dead idle is now 0.82 v and the throttle position mode at dead idle is now C/T.

Sparky: Glad everything worked out and your truck is fixed.