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I am actually in Western Kentucky. I just discovered some additional problems also. Brake lights not working when brake is depressed. Turn ignition to on, and turn signal indicators on dash flash really quick and front turn signals on car flash really quick, but rear turn signal lights do nothing. Could I also have a failed BCM? Could a failed BCM be causing all of these problems? Do I need to find a Tech2 to diagnose these issues? Would I be able to tell if the BCM is bad with a Tech2 scanner?
ahh your a couple states over from me. The turn signals in our cars do not go thru the BCM like newer vehicles do. The turn signal flasher is actually built into the hazard switch. It sounds to me there is a power and or ground issues suppling to various parts of the vehicle. I don’t feel the BCM is the issue. The brake lights are just controlled by the brake switch but maybe if I look up the wiring diagram for the brake lights and turn signals that are not working maybe that will tell us something. But as you can see from the previous wiring diagram you can see the turn signals and brake lights are fed from the same power the abs/pcm fuse gets as well. I am willing to be when you press the brake pedal you loose voltage at the abs/pcm fuse due to what I think is a bad connection somewhere in that circuit. At this point I don’t feel you need to rush out and buy a Tech II. I would also looks at the wiring harness under the hood and where they go thru the firewall and see if there is any parts that are damaged or frayed or hopefully no varmits have chewed into them.
ahh your a couple states over from me. The turn signals in our cars do not go thru the BCM like newer vehicles do. The turn signal flasher is actually built into the hazard switch. It sounds to me there is a power and or ground issues suppling to various parts of the vehicle. I don’t feel the BCM is the issue. The brake lights are just controlled by the brake switch but maybe if I look up the wiring diagram for the brake lights and turn signals that are not working maybe that will tell us something. But as you can see from the previous wiring diagram you can see the turn signals and brake lights are fed from the same power the abs/pcm fuse gets as well. I am willing to be when you press the brake pedal you loose voltage at the abs/pcm fuse due to what I think is a bad connection somewhere in that circuit. At this point I don’t feel you need to rush out and buy a Tech II. I would also looks at the wiring harness under the hood and where they go thru the firewall and see if there is any parts that are damaged or frayed or hopefully no varmits have chewed into them.
I did some more looking and testing. I did check the voltage to the ABS/PCM fuse while key in on position and tested full voltage. Pressed brake and no change in voltage. Also, when I tested the crank relay terminals with the multimeter the other night, putting the ground probe on the terminal 86 for ground and the red probe on 85 for power when the key is turned on, it showed full voltage, which indicated the ground was present to that ground terminal. I just tried something different. I clamped my test light to the battery positive and put the probe on the terminal that should be ground and nothing when key is turned to on or start position. Not sure why it grounds with the multimeter, but it isn't showing ground with the test light. This tells me that it isn't getting ground from the PCM (I assume). I did check all the main grounding locations, and all seem clean and tight. I am not seeing any damaged wiring anywhere. Since the vehicle has the new PCM (which I do believe was bad) and new Delco ignition, this still leads me to think it is either something to do with the passlock system, BCM, or possibly the neutral safety switch (Which is internal in the transmission on this car). I will try the whole relearn process once again. I wish there was some way to test that internal neutral safety switch to eliminate that as a problem. I still don't understand the no brake lights or rear turn signals. I also just remembered something. A couple months ago, this garage was struck by lighting. This did some electrical damage in the garage including some outlets being fried, etc. This car had a battery tender on it at the time. I didn't even think about this before, but now wondering if this is the root cause of all of these problems. The last time the car was driven before this incident, everything was perfect.
Correct, That is what I was saying earlier in a post about the crank relay not receiving a ground input. When a load is placed on the PCM ground to the relay it probably isn't there, not sure how the PCM is switching the relay, maybe a transistor and it has some bleed thru without a load on the output?
The pass lock voltage goes to the BCM and the BCM checks the previous stored voltage in memory and if it matches it will send a "password" via serial bus (same bus the scan tool communicates on) to the PCM to allow the PCM to crank the engine. But both the PCM and BCM Passlock password (assuming pass lock voltage is correct) has to be present for a vehicle start, in other words for it to ground the PCM relay. My question that I have asked a few times now is do you have voltage at the PCM/Crank fuse while trying to crank. If you do then we can take that out of the equation that the PCM is receiving the start input. My other question is, if you have someone turn and hold the key to the start position and then someone jumper out the starter relay contacts that engage the starter does the engine start? If the pass lock voltage is good with the PCM it should. All you are doing is bypassing the output of the PCM to the starter. But you will need two people for this test.
As for the neutral safety switch that is going to be read by the PCM and if your DIC is showing the gear ranges selected as you move thru them then I don't feel that is an issue.
Determination needs to be found on wether its a start command from the key switch circuit or is it one of the enablers the PCM has to see from the inputs like the transmission is in park or neutral to start.
However my concerns with other electrical problems makes me think there is a wiring issue in the car and it's not related to any modules. Personally if it were me I would want to troubleshoot and find out what is causing it rather than the shotgun approach which I feel you may be stating to proceed with. You have spent a lot of time and money on the car, I personally would want to know why I have to replace that item and not keep digging into my pockets and spending money I don't have to.
Correct, That is what I was saying earlier in a post about the crank relay not receiving a ground input. When a load is placed on the PCM ground to the relay it probably isn't there, not sure how the PCM is switching the relay, maybe a transistor and it has some bleed thru without a load on the output?
The pass lock voltage goes to the BCM and the BCM checks the previous stored voltage in memory and if it matches it will send a "password" via serial bus (same bus the scan tool communicates on) to the PCM to allow the PCM to crank the engine. But both the PCM and BCM Passlock password (assuming pass lock voltage is correct) has to be present for a vehicle start, in other words for it to ground the PCM relay. My question that I have asked a few times now is do you have voltage at the PCM/Crank fuse while trying to crank. If you do then we can take that out of the equation that the PCM is receiving the start input. My other question is, if you have someone turn and hold the key to the start position and then someone jumper out the starter relay contacts that engage the starter does the engine start? If the pass lock voltage is good with the PCM it should. All you are doing is bypassing the output of the PCM to the starter. But you will need two people for this test.
As for the neutral safety switch that is going to be read by the PCM and if your DIC is showing the gear ranges selected as you move thru them then I don't feel that is an issue.
Determination needs to be found on wether its a start command from the key switch circuit or is it one of the enablers the PCM has to see from the inputs like the transmission is in park or neutral to start.
However my concerns with other electrical problems makes me think there is a wiring issue in the car and it's not related to any modules. Personally if it were me I would want to troubleshoot and find out what is causing it rather than the shotgun approach which I feel you may be stating to proceed with. You have spent a lot of time and money on the car, I personally would want to know why I have to replace that item and not keep digging into my pockets and spending money I don't have to.
Sorry for my delayed response. I had to go out of town last week and just got back today. On the 10amp PCM (Crank) fuse, it is getting full voltage when the ignition is turned to start/crank. I did have my wife hold ignition in the crank position and jumped the crank relay terminals 87/30 and the car did start and ran fine. While running, still no brake lights or turn signals in the rear. Also, the TRAC OFF light was on. No other lights on DIC while running.
I kind of suspected you went out of town for Labor Day, hope you enjoyed your time away. It is great to hear it started by jumping out the relay!! Best news all day!! I have more homework for you.
I feel our next step is to either ohm the wire from the crank relay enable output from the PCM which is C2 Pin 76 to the crank Relay control ground Pin to see if we have a broken wire. I would also like for you to try and back probe the pin 76 of C2 connector of the PCM. (I assume you know this but the PCM is located inside the air filter box) with your test light to battery voltage and try to start the car ( leave the crank relay plugged in). I wan to see if the PCM is outputting the ground that drives the crank relay to turn on. If the test light lights up, then that tells me there is a broken wire between the PCM to the crank relay. Note there is a connector between C112 that is in between the PCM and Crank relay, I attached a location and pinout of that as well.
As for the Trac off, that can come on if the PCM has a trouble code and it disables the Electronic Brake Traction Control Module to operate the traction control system. Keep in mind the crankshaft variation learn has not been done yet since the PCM was replaced. That will have to be done after we get it starting correctly, need a scan tool for that. Lets visit that once we get the vehicle starting on its own with the key switch only. I do have one question though, does the ABS light illuminate when you turn the key on before you start it? It it doesn't then the ABS unit is not getting power and this would cause the Trac off as well.
The brake light and turn signal issue I attached a wiring diagram for it, I highly doubt all 4 bulbs burnt out at the same time, but might be worth checking with an ohm meter with the bulb removed. I have seen stranger things. I do have a question.. do the taillights illuminate when the headlights are on? Also does the center brake light turn on when you press the brake pedal? Again we can visit this more once we get the starting issue fixed.
Don't sweat the brake light and tac light on issue, lets take it one thing at a time. However thank you for letting me know you noticed that.
I also included a bulliten about the engine harness chaffing on the A/C condenser area.
Did your suggested testing this evening. Tested continuity on the wiring harness first. I have good continuity between PCM Harness C2 Pin 76 and the Crank Relay ground control terminal, so the wiring is good. I connected test light to battery + and PCM Pin 76 of C2 Connector and got nothing, so the PCM isn't outputting the ground. Was going to also check the bulbs in the tail lights, and realized the auto trunk release is also not operating. You also asked if the 3rd brake light was working when brake is depressed, and the answer to that is also no. No brake lights, no rear turn signals, no hazard lights in rear at all. The taillights do illuminate when the headlights are on.
Very interesting... does you scan tool have the ability to check diagnostics in the BCM? I went back and re read your original post and I noticed you said the radio displayed cal error. That is the anti theft activated in the radio. The radio is married to the vin that is stored in the BCM. Makes we wonder did in fact the lightning scramble the BCM like it did the PCM and the vin is not stored in there anymore. From what I recall the PCM and BCM vin have to match to start. Were you able to verify that when you reprogramed the VIN in the PCM? Since the PCM output is not grounding to power the crank relay, there has to be something the PCM is not happy with to enable a start.
Still doesn't explain the headlight/taillight/turn signal issue since they do not go thru the BCM. But the trunk pop and button do.
When it started the other day did all the gauges work on the instrument cluster? I think they get most of their data from the PCM. Does it tell you the trunk is open when you open it up?
Without being there this makes it difficult, maybe this is something we chat on the phone sometime about or facetime at some point?
I am not getting the CAL ERROR since replacing the PCM. I still think this is something to do with the Passlock Security, which leads me to a few questions that I hope you can answer.
When I do the relearn, I followed instructions I had exactly. Try to start car (No Start), release to ON position. Security light flashing for 10 minutes, then it goes off. Turn key to off position and wait a few seconds. Try to start car again (No Start), release key to ON position. Security light flashing for 10 minutes, then it goes off. And then a 3rd attempt of the same. After 3rd time, the security light goes off after 10 minutes, so I turn to off for several seconds. Attempt to start car, and still nothing, but when release to ON position the security light is NOT flashing any more. Does that mean the relearn was successful? The reason I am asking is that if I just turn the key to the ON position and DO NOT try to start the car, the Battery and Security flashes non-stop. Is that what it should be doing?
I can get in and see quite a bit of data in the PCM and BCM with my scan tool.
It does seem like all the gauges are live and working like they should when key turned to on position.
That is the correct procedure and if its not flashing then it has learned the new passlock value. with the key in the ON position and doors closed it should toggle from battery light and security until the key it turned off or vehicle is successfully started. (Battery then security then battery then security, etc). I would double check the vin numbers entered in both modules, PCM and BCM to make sure they match. I am not sure if it would flash the security light if the VINs didn't match. If you cant see the passlock data in your scan tool then you will probably need to find someone with a tech 2 to see what is actually going on.
