2000 GP GTP Electrical problems

Would someone who knows be so good as to explain where all (or as many as you know/are willing to explain) the main electrical grounds are on a 2000 GP GTP? I've got a bunch of accessories that all went out at once, and that's what I'm betting on. BTW: Checked the fuses (even under the hood) -- all good.

I have an Alldata subscription, but am no good at reading electrical diagrams.

If it helps, the accessories not working are: daytime running lights, power locks (though the relay under the dash clicks), radio (every aspect of it), lumbar adjustment, rear window defogger, and seat heater.

Everything else works fine, though I've had the infamous "rainwater onder the passenger floorboard" issue many times over (any grounds under there? My blower motor actually has rust on it). Auto AC is fine, as well as auto headlights, signal, parking, and dash lights, HUD, power seat, DIC, dome light, brake/backup lights, engine starting (still instantaneously after 5 years and 135000 miles, in fact) -- you name it.

Since all the accessories failed at once, simple logic says they must have a common problem, and I'm betting on a ground. If it helps, I first noticed one day when putting the car into park that the radio woud be "pulled down" (the display would temporarily fade), and it would turn off when shifting into park. This, I discovered, was due to the factory computer setup of auto-unlocking the doors when putting the gear selector into park. I disabled that and the problem went away, but the radio still continued to be a problem when going over bumps. The display and sound would dim, then return, then dim -- and finally faded away altogether. Also, the power locks tried to actuate (when I pressed the button or set the alarm), but seemed to lack sufficient power to trip completely. DRL faded away as well.

This originally happed in the summer of 2004. Last winter, on the coldest days, the radio display would return dimly, but no radio sound. Some current was still going to the radio, obviously, because the time was still correct, and the station buttons still held the correct frequencies. Also, the lumbar adjustment began working -- but only for a minute, then dead again (after warming up?). No such joy this winter, even with equivelent temps.

I've really got the feeling that this is something fairly simple -- a ground -- but finding it without any idea of where to look would be a fool's errand. So, again, can anyone point out WHERE and and all grounds are? In addition, what do they look like? I'm assuming a bunch of wires come together to a bolt, but will this always be at some otherwise blank spot, or might some grounds be located on an actual component -- like the blower motor? Any other ideas would be appreciated as well.

If you suspect grounding the best place to start is at the battery negative. From there all grounding terminates at the engine/transmission grounding stud which is located on the back of the engine (driver's, radiator side). There are also grounds located in the main engine compartment fuse box, the cabin fuse box and left side of the dashboard. In order to systematically check them you will need a GM Grand Prix service manual. All other reference sources are too generalized. Just about all of the ground wires are color coded black. All electrical components reference or require a ground in order for the circuits to work.

Also, your problem could be some component loading a respective circuit down or going South. About all you can do is visually inspect the grounds, make sure they are properly connected and tight. After that a wiring diagram and multimeter will probably be needed. With the proper documentation you should be able to troublesoot and see what is common to all the problems you are having.

I can't make any promises but I'll review the wiring diagrams and provide hopefully be able to provide a starting point.

BTW - Welcome to the forum.







http://i5.photobucket.com/albums/y186/lizzywiz/gtp.jpg
Thrasher CAI, DHP v1.0 PCM, SLP Headers,
3.25 SC pulley, CAIT GMAF, 2.5 DP/Hi-Flow CAT,
u-bend delete, 160 TS, ZZP Stage 1 72mm TB,
TB spacer, MSD 8.5mm wires, Autolite 103,
Goodyear Gatorback Serp. & SC Belt,
Nitto NT555R Drag Radials
1/4 ET: 13.210 sec. @ 104.490 mph
0 - 60 ft: 1.945 sec.

Those are all ignition controlled circuits (only have power when ignition switch is on). The radio clock and memory is a different circuit so that's why they are not messed up. Stick with checking the ignition controlled circuits to narrow your search. I would start with the ignition switch itself, then move on from there. Bob, are all those items controlled thru that module that leaves power on until you exit the vehicle? I don't think the DRL's are, so that may eliminate it as a culprit.

Those are all ignition controlled circuits (only have power when ignition switch is on). The radio clock and memory is a different circuit so that's why they are not messed up. Stick with checking the ignition controlled circuits to narrow your search. I would start with the ignition switch itself, then move on from there. Bob, are all those items controlled thru that module that leaves power on until you exit the vehicle? I don't think the DRL's are, so that may eliminate it as a culprit.

I'd go with your suggestion of looking at the secondary ignition circuits like IGN 2 and all accessories, etc. from the ignition switch on. Main Ignition is OK since engine starts and is running fine along with no other driveability problems. RAP (retained accessory power) is always involved in the accessories. With the power door locks acting up the BCM module could be suspect too or components associated with it like RAP and Theft Deterrent. Also, I wouldn't rule out the ignition switch assembly. They go bad on later model GPs too.









http://i5.photobucket.com/albums/y186/lizzywiz/gtp.jpg
Thrasher CAI, DHP v1.0 PCM, SLP Headers,
3.25 SC pulley, CAIT GMAF, 2.5 DP/Hi-Flow CAT,
u-bend delete, 160 TS, ZZP Stage 1 72mm TB,
TB spacer, MSD 8.5mm wires, Autolite 103,
Goodyear Gatorback Serp. & SC Belt,
Nitto NT555R Drag Radials
1/4 ET: 13.210 sec. @ 104.490 mph
0 - 60 ft: 1.945 sec.

Those are all ignition controlled circuits (only have power when ignition switch is on). The radio clock and memory is a different circuit so that's why they are not messed up. Stick with checking the ignition controlled circuits to narrow your search. I would start with the ignition switch itself, then move on from there. Bob, are all those items controlled thru that module that leaves power on until you exit the vehicle? I don't think the DRL's are, so that may eliminate it as a culprit.

Mostly true, but the power locks and lumbar adjustment have nothing to do with the ignition. They work (or, SHOULD) irrespective of the switch position.

Does that help?

Thanks for any and all comment.

I'm beginning to lean towards a BCM, ignition switch or battery problem since the affected accessories are both ignition controlled and "always live" circuits.

Did you say you have the schematic diagram of your car? That's the best tool you have. In it will show what accessories share a common source (common fuse, common relay, common module and alike)

On the lumbar problem it may be unique to itself or maybe associated with the BCM module. Lumbar uses the same "hot at all times" 12v as the rest of the power seats. Do the other power seat functions work? Have you inspected the wiring under the seat. There are two Lumbar Adjuster Relays. All ground wiring is black for those circuits. The ground point for lumbar is Ground G200 located under the left side of the dash which happens to be about the same location as the BCM. Plus check the electrical connectors to the BCM. I'd check the grounds at the lumbar relays with an ohmmeter and go from there.









http://i5.photobucket.com/albums/y186/lizzywiz/gtp.jpg
Thrasher CAI, DHP v1.0 PCM, SLP Headers,
3.25 SC pulley, CAIT GMAF, 2.5 DP/Hi-Flow CAT,
u-bend delete, 160 TS, ZZP Stage 1 72mm TB,
TB spacer, MSD 8.5mm wires, Autolite 103,
Goodyear Gatorback Serp. & SC Belt,
Nitto NT555R Drag Radials
1/4 ET: 13.210 sec. @ 104.490 mph
0 - 60 ft: 1.945 sec.

Did you say you have the schematic diagram of your car? That's the best tool you have. In it will show what accessories share a common source (common fuse, common relay, common module and alike)

He says he does but doesn't like reading schematics.

Me, I'm just pulling all my data out of my rear end even though I have a GM Grand Prix service manual. :biggrin:








http://i5.photobucket.com/albums/y186/lizzywiz/gtp.jpg
Thrasher CAI, DHP v1.0 PCM, SLP Headers,
3.25 SC pulley, CAIT GMAF, 2.5 DP/Hi-Flow CAT,
u-bend delete, 160 TS, ZZP Stage 1 72mm TB,
TB spacer, MSD 8.5mm wires, Autolite 103,
Goodyear Gatorback Serp. & SC Belt,
Nitto NT555R Drag Radials
1/4 ET: 13.210 sec. @ 104.490 mph
0 - 60 ft: 1.945 sec.

He says he does but doesn't like reading schematics.

Me, I'm just pulling all my data out of my rear end even though I have a GM Grand Prix service manual. :biggrin:



No, no... it's not that I don't LIKE reading schematics, it's that I don't know HOW.

I don't have the actual service manual, either. I have access to Alldata. Some schematics are available there, but I've had little success in trying to understand them and find common grounds between accessories.

On the lumbar problem it may be unique to itself or maybe associated with the BCM module. Lumbar uses the same "hot at all times" 12v as the rest of the power seats. Do the other power seat functions work? Have you inspected the wiring under the seat. There are two Lumbar Adjuster Relays. All ground wiring is black for those circuits. The ground point for lumbar is Ground G200 located under the left side of the dash which happens to be about the same location as the BCM. Plus check the electrical connectors to the BCM. I'd check the grounds at the lumbar relays with an ohmmeter and go from there.


In all your responses you continue to mention the BCM. Are you leaning toward that, or am I reading too much into it?

No, no... it's not that I don't LIKE reading schematics, it's that I don't know HOW.

I don't have the actual service manual, either. I have access to Alldata. Some schematics are available there, but I've had little success in trying to understand them and find common grounds between accessories.

It's not a problem, so don't feel bad. We're here to help. Automotive wiring diagrams are the worst around even the GM service manuals. People that can read or understand them have trouble. Is there any specific area you need reviewed? The people that did GM's technical documentation are either geniuses or stonewall idiots. I haven't figured out which yet. How is your troubleshooting technique and use of a multimeter?







http://i5.photobucket.com/albums/y186/lizzywiz/gtp.jpg
Thrasher CAI, DHP v1.0 PCM, SLP Headers,
3.25 SC pulley, CAIT GMAF, 2.5 DP/Hi-Flow CAT,
u-bend delete, 160 TS, ZZP Stage 1 72mm TB,
TB spacer, MSD 8.5mm wires, Autolite 103,
Goodyear Gatorback Serp. & SC Belt,
Nitto NT555R Drag Radials
1/4 ET: 13.210 sec. @ 104.490 mph
0 - 60 ft: 1.945 sec.

In all your responses you continue to mention the BCM. Are you leaning toward that, or am I reading too much into it?

The reason we're mentioning the BCM is because it's the heart of the interior electrical whereas the PCM handles engine/drivetrain. You mentioned shift interlock problems (BTSI) and power door locks acting up. The problem is troubleshooting the BCM is very difficult. Plus it's expensive so it's important to make sure it is the problem. The GM dealers will hookup a Tech II scanner and read any DTC codes that may be stored and perform a diagnostic procedure in a manual. Even if you were to replace the BCM, it would need to go to the dealer where it will be programmed for your VIN and options. I'd hold off for now on the BCM.

Are these items not working: daytime running lights, power locks, radio, lumbar adjustment, rear window defogger, and seat heater. Have you checked the fuse or 12v for lumbar/seat heater? The best I can do is review the wiring diagrams and see what's common. It takes time to piece it together. Based on how your radio is working, I'd say there is a short and it just a matter of figuring out where. It could be as simple as a fuse, relay or wiring.







http://i5.photobucket.com/albums/y186/lizzywiz/gtp.jpg
Thrasher CAI, DHP v1.0 PCM, SLP Headers,
3.25 SC pulley, CAIT GMAF, 2.5 DP/Hi-Flow CAT,
u-bend delete, 160 TS, ZZP Stage 1 72mm TB,
TB spacer, MSD 8.5mm wires, Autolite 103,
Goodyear Gatorback Serp. & SC Belt,
Nitto NT555R Drag Radials
1/4 ET: 13.210 sec. @ 104.490 mph
0 - 60 ft: 1.945 sec.

It's not a problem, so don't feel bad. We're here to help. Automotive wiring diagrams are the worst around even the GM service manuals. People that can read or understand them have trouble. Is there any specific area you need reviewed? The people that did GM's technical documentation are either geniuses or stonewall idiots. I haven't figured out which yet. How is your troubleshooting technique and use of a multimeter?

I have a small digital autoranging multimeter, and understand it fairly well. I have no experience doing auto electrical troubleshooting, but am willing to learn to save myself the potentially enormous expense of having a shop do it.

You mentioned shift interlock problems (BTSI) and power door locks acting up.

Are these items not working: daytime running lights, power locks, radio, lumbar adjustment, rear window defogger, and seat heater. Have you checked the fuse or 12v for lumbar/seat heater? The best I can do is review the wiring diagrams and see what's common. It takes time to piece it together. Based on how your radio is working, I'd say there is a short and it just a matter of figuring out where. It could be as simple as a fuse, relay or wiring.


No shift interlock issue; was just saying that I originally discovered the problem when shifting into park because that would cause the doors to unlock, which pulled the radio down.

You're correct about which items are failing. I've checked ALL fuses (near the glove box as well as the fuse block under the hood -- unless there are others). Haven't checked power other than running a multimeter across the fuse contacts of some of the failing devices. Unfortunately, I don't remember the results. Can do it again tomorrow though if it might help.

No shift interlock issue; was just saying that I originally discovered the problem when shifting into park because that would cause the doors to unlock, which pulled the radio down.

You're correct about which items are failing. I've checked ALL fuses (near the glove box as well as the fuse block under the hood -- unless there are others). Haven't checked power other than running a multimeter across the fuse contacts of some of the failing devices. Unfortunately, I don't remember the results. Can do it again tomorrow though if it might help.

Sounds good. I'll give you the components of where to measure voltage. It will be at the engine compartment fuse box to start. I'll compile the info from the service manual and post it in the morning. If you could record the readings and we can go from there.






http://i5.photobucket.com/albums/y186/lizzywiz/gtp.jpg
Thrasher CAI, DHP v1.0 PCM, SLP Headers,
3.25 SC pulley, CAIT GMAF, 2.5 DP/Hi-Flow CAT,
u-bend delete, 160 TS, ZZP Stage 1 72mm TB,
TB spacer, MSD 8.5mm wires, Autolite 103,
Goodyear Gatorback Serp. & SC Belt,
Nitto NT555R Drag Radials
1/4 ET: 13.210 sec. @ 104.490 mph
0 - 60 ft: 1.945 sec.

Here's the best starting point. In engine compartment fuse box look for Fuse #4 which is marked BATT MAIN 2. It's the common point for everything except DRL which we should assume is a separate problem for now. BATT MAIN 2 feeds the seat circuit breaker, rear defogger fuse and relay, heated seat/lumbar fuse and relay, and the power door lock fuse (BCM input). There should be approximately 12 v.d.c. referenced to ground. You can just pull the BATT MAIN 2 fuse and measure at the fuse socket. Also check the fuse and make sure it isn't blown. I'd use a multimeter in ohms position just to be sure.

Good luck and let me know what it reads.







http://i5.photobucket.com/albums/y186/lizzywiz/gtp.jpg
Thrasher CAI, DHP v1.0 PCM, SLP Headers,
3.25 SC pulley, CAIT GMAF, 2.5 DP/Hi-Flow CAT,
u-bend delete, 160 TS, ZZP Stage 1 72mm TB,
TB spacer, MSD 8.5mm wires, Autolite 103,
Goodyear Gatorback Serp. & SC Belt,
Nitto NT555R Drag Radials
1/4 ET: 13.210 sec. @ 104.490 mph
0 - 60 ft: 1.945 sec.[/QUOTE]

Here's the best starting point. In engine compartment fuse box look for Fuse #4 which is marked BATT MAIN 2. It's the common point for everything except DRL which we should assume is a separate problem for now. BATT MAIN 2 feeds the seat circuit breaker, rear defogger fuse and relay, heated seat/lumbar fuse and relay, and the power door lock fuse (BCM input). There should be approximately 12 v.d.c. referenced to ground. You can just pull the BATT MAIN 2 fuse and measure at the fuse socket. Also check the fuse and make sure it isn't blown. I'd use a multimeter in ohms position just to be sure.

Good luck and let me know what it reads.

I pulled the fuse and checked it visually, as well as with the meter set for continuity. Definitely GOOD.

By "referenced to ground," did you mean, across the terminals? Doing that gives me zip, zero, nada -- withg the ignition on or off. Ohm setting gives me the same. Guess the fuse HAS to be good then, eh? ;)

Question: could I TEMPORARILY run a grounding wire to one of the fuse clips to see if this would restore my accessories? Didn't want to do this without asking someone who knows, as I don't want to fry anything!

I pulled the fuse and checked it visually, as well as with the meter set for continuity. Definitely GOOD.

By "referenced to ground," did you mean, across the terminals? Doing that gives me zip, zero, nada -- withg the ignition on or off. Ohm setting gives me the same. Guess the fuse HAS to be good then, eh? ;)

Question: could I TEMPORARILY run a grounding wire to one of the fuse clips to see if this would restore my accessories? Didn't want to do this without asking someone who knows, as I don't want to fry anything!

I would not recommend running any ground to any fuse terminal unless you want to see smoke.

Just to be safe on same sheet of music, what I mean reference to ground is: With meter in dc volts position, fuse pulled out of socket, hold the black lead to the battery negative post and the red lead to any one of the fuse socket terminals in the fuse box. (BATT MAIN 2 only for now). Check both terminal points with the red lead because only one of them will give you around 12 vdc. One will read zero volts.

To check resistance across the fuse put meter in ohms. Remove fuse, hold in hands only, then hold red lead across one fuse terminal and black lead across the other. Meter will read continuity or "0". If reads "0" fuse in good. If reads "infinite" or meter reading doesn't change fuse is bad.

BTW - Ignition switch should be off and key removed.

And the 12v should be present on the right side fuse socket electrical contact.

I measured mine and get 12.4 volts d.c.







http://i5.photobucket.com/albums/y186/lizzywiz/gtp.jpg
Thrasher CAI, DHP v1.0 PCM, SLP Headers,
3.25 SC pulley, CAIT GMAF, 2.5 DP/Hi-Flow CAT,
u-bend delete, 160 TS, ZZP Stage 1 72mm TB,
TB spacer, MSD 8.5mm wires, Autolite 103,
Goodyear Gatorback Serp. & SC Belt,
Nitto NT555R Drag Radials
1/4 ET: 13.210 sec. @ 104.490 mph
0 - 60 ft: 1.945 sec.

I would not recommend running any ground to any fuse terminal unless you want to see smoke.

Just to be safe on same sheet of music, what I mean reference to ground is: With meter in dc volts position, fuse pulled out of socket, hold the black lead to the battery negative post and the red lead to any one of the fuse socket terminals in the fuse box. (BATT MAIN 2 only for now). Check both terminal points with the red lead because only one of them will give you around 12 vdc. One will read zero volts.

To check resistance across the fuse put meter in ohms. Remove fuse, hold in hands only, then hold red lead across one fuse terminal and black lead across the other. Meter will read continuity or "0". If reads "0" fuse in good. If reads "infinite" or meter reading doesn't change fuse is bad.

BTW - Ignition switch should be off and key removed.

And the 12v should be present on the right side fuse socket electrical contact.

I measured mine and get 12.4 volts d.c.

12.54 - 12.58 VDC
Fuse: good

Next?

12.54 - 12.58 VDC
Fuse: good

Next?

Good. We can go forward from there. It will branch off and feed the pertinent fuses and relays. Send me a PM email and regular email address and I'll send you the wiring diagram showing the circuit and where to troubleshoot next. That way we don't have to go back n forth piecemeal.








http://i5.photobucket.com/albums/y186/lizzywiz/gtp.jpg
Thrasher CAI, DHP v1.0 PCM, SLP Headers,
3.25 SC pulley, CAIT GMAF, 2.5 DP/Hi-Flow CAT,
u-bend delete, 160 TS, ZZP Stage 1 72mm TB,
TB spacer, MSD 8.5mm wires, Autolite 103,
Goodyear Gatorback Serp. & SC Belt,
Nitto NT555R Drag Radials
1/4 ET: 13.210 sec. @ 104.490 mph
0 - 60 ft: 1.945 sec.

bnaylor get real ,your gp would go 0 to 60 that fast unless you dropped
it out of a plane...get real im sure someone still thinks your cool...posting pics of gp's you seen online and reffering to the equipment in your car with no research as to whether it would fit or not.
but hey thats ok ..whatever helps you sleep at night.

bnaylor get real ,your gp would go 0 to 60 that fast unless you dropped
it out of a plane...get real im sure someone still thinks your cool...posting pics of gp's you seen online and reffering to the equipment in your car with no research as to whether it would fit or not.
but hey thats ok ..whatever helps you sleep at night.

What has my GTP got to do with electrical problems? Are you here to help or criticize?

BTW - Just what part of 0 - 60 ft do you not understand? And I've jumped out of an airplane more than once. :biggrin:








http://i5.photobucket.com/albums/y186/lizzywiz/gtp.jpg
Thrasher CAI, DHP v1.0 PCM, SLP Headers,
3.25 SC pulley, CAIT GMAF, 2.5 DP/Hi-Flow CAT,
u-bend delete, 160 TS, ZZP Stage 1 72mm TB,
TB spacer, MSD 8.5mm wires, Autolite 103,
Goodyear Gatorback Serp. & SC Belt,
Nitto NT555R Drag Radials
1/4 ET: 13.210 sec. @ 104.490 mph
0 - 60 ft: 1.945 sec.

I am new to this discussion, if you havent fixed this yet..... I have a 98 GTP. It intermittently lost power to heated seats, daytime driving lights, driver info center, heater fan, A/C compressor and rear window defogger. The control realys for all of these devices get their power from the hvac/dic fuse. this fuse gets its power from one of the contacts on the ignition switch. the ignition switch has 6 circuits, 2 of them control power when the switch is in run. one of them powers the above mentioned fuse. Use of a voltmenter isolated the problem to the switch itself(everything else in the car worked fine). I replaced the switch($94) and everything works fine. I destroyed the switch and found a bent contact.

I did buy the 3 book set of official manuals(about 30 lbs) to find this.
Replacing the switch is not trivial and required that i make a funky reverse torx socket. if you want to try, i can provide hints. the manual instructs you to de-activate and remove the air bag and steering wheel(not for the weak of heart!), turns out you dont really need to. I suggest you get a quote from the dealer. should take ~ 2hours