Dec 112019


My truck anti theft deterrent system activated and would not allow car to start. After tinkering with the system 3 days and inspecting parts and wires I had it towed to dealer for diagnostics. The mechanic says I need the theft deterrent module replaced. I asked if the module is the one located around the ignition switch (i have been researching online all weekend and even took panels off to see the part beforehand). He says no it is the entire module that is under the dash. When my fiance asked if it is located behind the radio compartment he said yes.

Well I have researched a lot and only see that there is a theft control module which is by the ignition which ties into I believe the BCM which is located under the drivers dash panel where my parking break release and steering column is.

So what is located behind the radio? Is there some other module I am not seeing? I have a 2007 Chevy Tahoe LTZ 5.3L v8 flex. I feel like I am being lied to and just told any and everything. His responses are very vague and I am someone who wants to know exactly what my money goes to.

The part number he gave me for what he said has to be replaced is in fact the theft control module that attaches to the ignition cylinder. Can someone give me a diagram of the entire Passkey 3 system in a Chevy Tahoe? Is it tied directly to the BCM as I thought? And if that is replaced does it require relearning the key with a scan tool or can the key be relearned by the 10 minute increments relearn method repeating 3 times?

Under replacing Body Control Module (BCM) the Repair Manual states:

This procedure must be performed if the BCM, Passlock sensor or PCM is replaced. If BCM is not properly programmed, it will not control all the features properly.

  1. Ensure battery is fully charged and ignition switch is in the ON position.
  2. Connect a suitably programmed Tech II, or equivalent, scan tool to Data Link Connector (DLC).
  3. Access scan tool “Special Functions” menu and follow scan tool instructions to program BCM.
  4. If BCM fails to accept the program, inspect all BCM connections and ensure scan tool is equipped with latest software.

The PCM, BCM and Passlock sensor all communicate with each other but are separate modules. Theft deterrent programming(see below) must be performed anytime the BCM, PCM or Passlock sensor is replaced.

As for feeling like the dealer is giving you the run around. In most cases the dealership hires a sales rep for their Service Writer position. They are good at selling and usually not skilled mechanics. They rely on what the mechanics diagnosis is for each repair and build an estimate based on what parts are looked up by the mechanic. They then, to the best of their ability, try to explain this to the customer. In most cases they have no idea what is going on with your car or even know what color it is. They are more of a middleman between the customer and the mechanic. I wouldn’t hold there lack of knowledge against them.

Theft Deterrent Control Module Location

Right side of the steering column near the ignition key cylinder


Anti-Theft System Diagnostic Service, Test

A visual inspection must always be performed to confirm the presence of aftermarket components, potential collision damage, or areas of concern.

Most systems use a key with transponder, transponder receiver, transponder module and PCM, BCM or stand alone anti-theft module to control system.

The transponder equipped key is inserted into the ignition cylinder and the ignition switch is turned on. The transponder module wakes up and comunicates with the transponder receiver to determine if the appropriate key was used. If the key matches, the transponder module sends a signal to the PCM authorizing vehicle start. If the key does not match, the vehicle will not start and the security lamp will flash.

If vehicle has had a module replacement, a perimeter reset/module pairing, may be required before anti-theft system will operate correctly.

If vehicle is equipped with tow-away protection, antitheft can be sounded when vehicle is being transported.

Some models may have a anti-theft code recorded in radio, retrieve radio code prior to servicing.

Some models may be equipped with a manufacture assisted satellite anti-theft system. Review vehicle owners guide for more information.

1. Duplicate customer concern.

2. If vehicle is equipped with tow-away protection verify that it is disabled.

3. If vehicle is equipped with a interior motion sensor, verify there is nothing hanging from rear view mirror or coat hangers as this can trigger an anti-theft event.

4. If vehicle is equipped with a interior motion sensor and auxiliary heating system, one system should be deactivated as auxiliary heating system can trigger a anti-theft event.

5. Inspect for aftermarket components, such as a remote start or alarm.

6. Verify that hood, luggage compartment, and all doors are fully closed.

7. Verify battery is at full state of charge. Inspect battery condition and charge batteries, as required. An overcharge condition may also affect anti-theft system operation.

8. Ensure transponder key does not required battery replacement.

9. Inspect related fuses and fusible links.

10. Inspect condition of anti-theft lamp. If lamp is flashing perform following:

a. Remove any signaling devices or magnetic cards from key-chain and attempt to start.

b. Verify concern is present with each vehicle key. If concern related to one key, reprogram key and reevaluate system operation. If concern is still present with only one key, a replacement key is required.

c. Connect a suitably programmed scan tool to vehicle.

d. Perform network test and verify communications.

e. Inspect state of hood, luggage compartment, and all doors to verify showing closed on scan tool.

f. Verify programming of all keys. A system reset and reprogramming of all keys at one time may be required.

g. Retrieve any anti-theft related diagnostic trouble codes (DTCs) and follow appropriate DTC code diagnostics.

Theft Deterrent System Programming

The following procedure must be performed anytime the BCM, PCM or Passlock sensor is replaced.

1. Ensure battery is fully charged and there are no Diagnostic Trouble Codes (DTCs) present.

2. Turn ignition switch from the OFF position to the CRANK position attempting to start the vehicle. Vehicle should start and then stall.

3. After vehicle stalls, leave ignition in the ON position and observe security indicator on instrument cluster.

4. When security indicator turns off, turn ignition switch off and wait 10 seconds.

5. Repeat steps 2 through 4 two more times (3 times total).

6. BCM and PCM will learn the new code on the next start attempt.

Nov 182019

1999 Chevy Tahoe

I was giving gas but wasn’t speeding up

2001 Chevy Tahoe 4×4, have never had any symptoms of transmission issue, slipping, dummy light, etc. before. I hit a raccoon last week. Think impact was more on passenger side of undercarriage. Approximately 1-2 miles after hitting raccoon, I noticed I was giving gas but wasn’t speeding up so,I let off gas and everything seemed to be okay intel I would give gas to speed up. I could hear engine accelerate but transmission didn’t seem to be engaging, so I I let off gas drove about half mile pulled over to check, put in reverse u could hear engine accelerate but no movement, so put back in park shut off to wait for hubby. After about 5 min decided to turn back on put it in gear functioned normally for short distance but then same issue again, engine accelerate but no’s shift, (a mile at most )shut off again waited approximately 5 minutes turned on fine then same issue., so pulled over waited for hubby to come get.

No dash lights ever came on, no burning smell from engine or transmission to indicate getting hot during all this.

No previous warning signs

No previous warning signs to indicate transmission problems ever before this incident, hubby added transmission fluid assuming cause was low fluid ended up not being low so we had to drain back out. Fuses seem to be good. Took pan off didn’t see any shavings or anything. Don’t think burnt out trans because like I said never got hot or anything before or after this incident. I feel has to be related to raccoon accident because I know I didn’t drive more than 2 miles when it started having problems and never had any issues before.

Is there something underneath, plug sensor, etc that could have gotten broken knocked loose from Impact of raccoon.

The transmission cooling lines/hoses are on the passenger side. They may have been bent or kinked and no longer allowing the fluid to flow. This would cause an issue. That would be the first thing to look at and consider as you have already ruled out the possibility of transmission fluid level low.

How to Replace Lower Transmission Cooling Hose


Nov 072019

Chevy tahoe

My cigarette lighter and all of the accessory outlets are not working. I checked the fuses and they are not the problem. Are these all wired together to a junction box, module, or voltage regulator? Can’t charge my phone in the truck….aaarrggghh

Are you sure the charge cord is good?

There are separate fuses for the each outlet including the one in the rear. So make sure you check the appropriate fuse. After looking over the wiring diagram for the accessory outlets and cigar lighter there is a common. The common here would be the ground connection.  If you have a volt-meter you can check for 12 volt positive and 12 volt negative ground at each outlet to determine if the wiring is good or if the outlets are faulty. You can also use a test light if you have one handy to check it as shown in video below.

Accessory Outlet Wiring Diagram


Using a Test Light to check your accessory power outlets

Cigar Lighter Socket and Removal Tool by Dorman

Odometer display codes 2007 Chevy Colorado

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Oct 262019

Chevy Colorado

I’m curious where my odometer normally reads it has a strange set of numbers. 13 16 10. I was only a mile and a half or so from home and the last number changed 10 11 12 ending on 13 16 15. Can’t seem to find anything anywhere to tell me what this means. My apologies if this is a stupid question… But hopefully you can tell me what this is and why it’s there. 

Camano Island WA

odometer display code

Was unable to locate any information on this as well. I will post it in case someone else has seen it they can respond.

You could try this reset method to see if it clears. Then test to see if it comes back.

Reset Stem Method

1. Turn ignition switch to RUN position, but do not start engine.

2. Press and hold reset stem in lower center of instrument cluster until Oil Life message is displayed.

3. Once alternating OIL LIFE and RESET messages appear in display, press and hold reset stem until several beeps sounds This confirms oil life system has been reset.

4. Turn ignition key to Lock position. If CHANGE/OIL message comes back on when engine is started, engine oil life system has not reset. Repeat procedure.

Alternate Method

1. Turn ignition On, but do not start engine.

2. Fully depress and release accelerator pedal three times within 5 seconds. Several beeps will sound. This will confirm system has been reset.

3. If CHANGE ENGINE OIL lamp flashes for 5 seconds, this indicates system has reset.

4. Turn ignition key to Lock position. If CHANGE/OIL message comes back on when engine is started, engine oil life system has not reset. Repeat procedure.

4×4 Indicator light 2000 Chevy Silverado 2500 LS V8 6.0L 4×4

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Oct 162019

2000 Chevy 2500

When my truck idles their is no whine. When my truck warms up and i drive it for a little bit and I stop at a red light or a stop sign and then accelerate that is when the whine starts. It also makes the accelerator vibrate just a little. I have a hydrobooster leak which causes the power steering fluid level to go down. I also have an issue with my 4×4. I have no lights on the indicator and no service 4 wheel drive message either. The indicator has been replaced along with the TCCM. Fuses have been replaced. I got told a sensor but what sensor and where would it be?

Whine Noise

The whine is from the power steering system having air in it. This will continue as long as the leak is not taken care of. The worst case scenario would involve replacing the power steering pump itself.

No 4×4 Indicator Lights

The most likely sensor that would be involved would be the selector switch. There is a chance that the wiring is the issue. Use the wiring diagram below for reference.

Automatic Transfer Case Select Switch Wiring Diagram




Lean Condition 1986 Chevy Camaro 2.8 MPFI

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Oct 162019


Need help diagnosing lean condition, poor acceleration. Have had two shops try to fix with no luck. Did some parts shot gunning myself but still no change.

In 1986 almost all manufacturers decided to go with excessive vacuum controls on the engine. The most common cause of a lean condition is related to a vacuum leak. With this engine having so many vacuum lines I would start there first and then consider the intake gasket may also be leaking due to age. Lastly check the fuel injectors. There is a technical service bulletin out that concerns the fuel injectors becoming clogged and causing a lean condition and a lack of power.

TSB# 03-06-04-030F


When I close my door  none of the gauges work 2007 Chevy Impala LS

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Oct 162019

2007 Chevy Impala

I hit a super pothole in the street, it has done something to the electric system in the car. when my car door is open, all of my panel gauges work correctly. When I close my door  none of the gauges work and a message pops up constantly telling me my door is open. It also drains my battery in a couple hours. What could be the cause of this and how do I fix it ?

Certainly has to do with the electrical system. Most likely an issue with the door jam button. But may not be limited to just that. In fact it is quite common for the wiring harness that runs between the door and the body to develop an issue. This is in part do to the fact that the drivers door gets opened and closed more often then the other doors. Add in some age on top of that and the wiring becomes brittle.

First look at the wiring harness near the door jam for damage. Next look for shorted and open wiring. Since everything seems to work when the door is open you will need to wiggle the wiring during testing to get the best results.

No Start 2011 Chevy Traverse

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Oct 092019

2011 Chevy Traverse

I recently replaced the ECM in my Traverse. It was driving and running good. I went to give it gas to pull a mountain and it went into a lower gear and would not shift out. By the time I got to the top of the mountain it was running hot. After it cooled off, I started it and headed home. After driving about 4 miles it died again (not hot) and now it will not start. I can turn the key over and it sounds like a car with a dead battery trying to start. My battery amp goes to 0 and the lights dim, but the battery is brand new. What could be causing my problems?? I’m scared to death the engine is locked up

It is possible that the alternator is failing to charge the new battery. Or the alternator belt came off. You would have lost power steering if that was the case though. I would start off by fully charging the battery and checking the battery cable connections. If you are hearing a bunch of clicks (click, click, click, click) when trying to start the engine, that would indicate a weak battery. One HARD Click would indicate a faulty starter. No Noise at all would indicate dead battery or loose connections or bad starter relay. In any case we have developed a step by step chart to assist in diagnosing a no start condition.

Fouling spark plugs and burning oil 2006 GMC Sierra 2500HD 8.1L

 Auto Repair Questions, Chevy, GMC  Comments Off on Fouling spark plugs and burning oil 2006 GMC Sierra 2500HD 8.1L
Oct 052019

2007 GMC Sierra

Engine burning oil

This question is in regard to a 2006 GMC Sierra 2500HD (8.1L gas engine) with 197,000 miles on it. It had around 60k or 70k miles when I bought it in 2012. It has had a rough life since then – lots of hauling and towing. It has had a long-running problem of burning oil (I would have to add some oil every month), but the oil-burning has suddenly gotten much worse, and I am adding oil every few days.

Every mechanic I’ve ever taken the truck to always says “that’s just what old trucks do, they burn oil”. Another problem (which I assume is related) is that the spark plugs get ruined frequently and have to be changed. I’ve had to change them at 124k miles, 130k (wires only), 170k, 183k, and 197k. At 197k, I told the mechanic I was tired of spending so much on spark plugs, and we decided to try a cheaper plug and see what happens. This, in addition to a full tune-up/fluid exchanges, fixed the symptoms I was seeing (intermittent shudder when idling, ‘check engine’ light coming on when going uphill over 45mph, engine misfire code P0300).

But then I only made it 1200 miles before those same symptoms returned. Same P0300 code, one ruined spark plug, cylinder 2. A mechanic replaced that one plug, and I made it another 80 miles before things went south again yesterday. This time it’s 2 plugs, cylinder 2 and another cylinder (he didn’t tell me which one). So we’re replacing all plugs with the better double platinum ones.

Any ideas what is going on? Am I just doomed to replace the plugs every 15k miles from now on? I love this truck and don’t want to get rid of it. For anyone interested, there are more details below, in case they provide any additional clues. Thanks in advance!

Full Maintenance History

  • oil changes are done every 5k miles
  • oil cooler lines replaced in 2013
  • major tune-up at 124k miles (transmission flush, coolant flush, 4×4 service (front/rear differentials, transfer case), spark plugs, fuel induction system service, air filter replaced)
  • 130k, replaced spark plug wires, cleaned mass air flow sensor
  • 132k, replaced fuel pump assembly
  • 169k, code P0171, cleaned mass air flow sensor
  • 170k, replaced spark plugs, plug wires (mechanic said plugs were really bad and covered in oil)
  • 174k, replaced air filter
  • 183k, replaced spark plugs and air filter
  • 1955xx miles, replaced serpentine belt, belt tensioner, and fan clutch; mechanic said spark plugs are misfiring/worn out (but I couldn’t afford to replace them yet); mechanic said “we took off the valve covers and looked inside of the cylinder heads, in case the valves are gummed up. But we didn’t really find anything except the piston rings are a bit burned out.” He recommended trying Lucas oil stabilizer and Lucas fuel cleaner (which I did) and using premium gas and higher quality synthetic oil from now on (which I did). He said the engine is burning lean, so better fuel will help that. Told me to get a tune-up as soon as I can.
  • at 197k, ‘check engine’ light came on every time going uphill over 45mph; code was P0300 (engine misfire; no other codes); idle is very rough; replaced spark plugs/wires with cheaper copper plugs as an experiment, did fuel exchanges (differentials, transfer case, transmission (& filter), coolant, power steering fluid); cleaned the air filter
  • 1200 miles later, replaced 1 spark plug; added “Engine Restorer 8-Cylinder” to the oil, as recommended by the mechanic
  • 80 miles later (today), replacing all spark plugs with the right kind. Mechanic says it will take a while of driving at high speeds for the “Engine Restorer” to work?

I travel a lot, so I rarely get to use the same mechanic. Whenever I go to a new mechanic, they usually tell me that my last mechanic was BS-ing me and/or didn’t know what he was talking about. I’m a car dummy, so I have to just take the word of these mechanics, and I never really know when I’m getting the run-around.

Thanks to anyone who made it this far in my post!
(attached photo is the cheapo copper spark plug after 1200 miles)

Oil Fouled Spark Plug

Print a copy of your history and present it to your next mechanic, they will appreciate knowing what you have already gone through.

Chevy engines burn oil. This is true but they shouldn’t foul the plug in 1200 miles. You have something else going on.

Definitely fouling the spark plug. So the engine is going to store the P0300 – Engine Misfire code when this happens. That is normal during this situation. There are several things that can cause this code and situation.  The good news would be that you have tried a few things that tell us which cylinders are the problem cylinder.

Compression Test

The next thing to do would be to have a compression test performed. This information can sometimes explain a lot of whats going on. And this will confirm the problem cylinder/s.

Head Gasket

If two cylinders next to each other are significantly lower than the rest there is a possibility of a blown head gasket. However a blown head gasket would also be followed by white exhaust smoke and coolant loss. Since you didn’t mention any of those symptoms we will move on.

Fuel Injector

If there is specifically one cylinder that keeps fouling out the spark plug there is a chance of the fuel injector being stuck OPEN(ON). When this occurs the cylinder rings will wash out(unseat) and foul out that spark plug. After time the the excessive fuel being dumped into the cylinder with washed out rings will allow the fuel to seep into the crankcase and contaminate the engines oil. When this happens you will notice excessive exhaust smoke and start fouling out additional spark plugs.

When looking at the oil on the dipstick it may also have a fuel smell. A quick test can be to remove the spark plugs from the effected cylinders and cycle the fuel pump on and off a few times. While keeping at a distance to prevent fuel from shooting out at you, look to see if the cylinder fills with fuel. If you find the fuel injector is stuck open you will need to replace it and and then perform an oil change to remove any contaminates oil.

Hole or Crack in Piston

You didn’t mention it but i want to cover engine ping. If you experience the engine pinging when climbing a hill or under heavy acceleration you may have caused internal damage. Continually driving the vehicle under these conditions will burn a hole in the piston. If this is the case you will have 0 compression and oil foul the spark plug quickly.

Worn Valve Guides and seals

When the valve seals or guides are worn you will see a puff of smoke at start up. Sometimes lasting until the engine reaches operating temperature. This usually occurs after the vehicle has had time to set and the oil drains down past the guide seals and into the cylinders.

Engine Misfire Causes

  • Faulty spark plug (s)
  • Faulty ignition coil (s) – Engine Coil
  • Ignition coils harness is open or shorted
  • Ignition coils poor electrical connection
  • Clogged or faulty fuel injectors
  • Injectors harness is open or shorted
  • Injectors poor electrical connection
  • Improper spark plugs
  • Insufficient cylinders compression
  • Incorrect fuel pressure
  • Intake air leak


2009 Chevy Malibu wont accelerate

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Oct 032019

Chevy Malibu

I drive a 2009 Chevy Malibu. While driving it sometimes feels like when you push the gas pedal it doesn’t want to gain speed. Finally you’ll feel a shift and it’ll start to climb speed. Sometimes it won’t accelerate over 50 and when it does my traction control light comes on and esc warning. Any ideas on how to fix this?

  • If the RPM are climbing higher and not moving the car accordingly then it would appear the transmission is slipping. How high does the RPM go without moving the car significantly? If the problem is transmission related, the cheapest/easiest thing to try would be to add a little transmission fluid if it is low.
  • Perhaps the Catalytic converter is plugged. It’s been known to happen.

Source: Drunken Elvis

  • If one of the cats is plugged, usually you can tell by letting the car idle for 20-30 minutes. The plugged cat should be very hot, they will even get hot enough to glow red in the dark if they run long enough. You could try checking it after a long drive, see if one is noticeably hotter. (Use an infra red temperature gun for testing temperature of converter, do not touch)

Source: SBUBandit