Thread: 2004 Grand Prix GTP Supercharged Issues

Hello,

I found this forum searching google for issues to my 2004 GTP. Here is the timeline of what I'm experiencing and everything I've done since.

On March 28th, I drove to Nashville from Sarasota, Florida with no issues and woke up on the 29th and drove 5 miles to a concert venue. Had no issues at all up until after the concert. I started my car up no problem and this is when things started going wrong. The radio shut off and the dash started giving me things to do(Security System Maintenance and Traction Control Maintenance) but the car was still running. So, thinking the computer was going crazy, I turned the car off to reset it and when I went to restart it, it wouldn't start. It would just give a click when I tried to turn it over.

I had it towed to the nearest garage where the next morning they called me and the car started fine with no issues. They told me they were thinking it could be an ignition switch/tumbler issue(which I had an issue back in December with the heater that I've read has been the cause of the ignition switch going bad) and that the Chevrolet dealership was 2 miles away, so I drove it over there and had them check it out. The called me a few hours later and said the battery, alternator, and starter were fine. They said everything seemed fine with the ignition switch/tumbler, but I decided to have it changed anyways as it seemed the most sensible issue(note: They turned the car on and off over 50 times and didn't have one issue starting the car).

So, car finished, I drove home on April 1st(2 extra nights in Nashville this issue has cost me $800 with hotel and car fix) and made it back to Sarasota with zero issues. So thinking everything was fixed, I drove to Jacksonville, Florida on April 9th(I only drove the car like 15-20 miles since I had got home from Nashville before this trip) and everything was going great until I got about 15 minutes from Nashville. As I'm on the I10 heading East, all of a sudden the radio shuts off for about 5 seconds and turns back on, the security system maintenance and traction control maintenance also comes on again. Car is running fine, so I finish my drive to Jacksonville. I park the car and I turn it off, so I decide to see if it will start back up and it does, no issues. So I go and enjoy my evening and after the night was over, I go to drive back home and again, the car won't start giving me the same click noise when I try to turn the car on(again, no radio working...forgot to note: all the lights work on the dash, overhead, brake lights, head lights, windows, etc), so I end up spending the night as my friends were staying.

Next morning before we go to eat lunch, I try to start the car and again, it won't start. We go to eat for about 2 hours and walk back, I tell them let me see what happens and this time it starts like normal, no issue. Drove back with zero issues and hasn't happened since(again, only have driven it like 25 miles, but I have started it about 50 times since just to see if it'll happen again).

So, as I look up issues, I'm thinking the passkey is having issues, but I'm not getting car won't start due to security system like most people get. I will say the car has an aftermarket remote start and I tried to start the car using that and it won't start(it bumps the starter and turns the radio/lights on but won't turn over. It also tries to start itself 4 times without hitting the button after the 1st try).

I took it to my local Chevrolet Dealer and discussed with them and this is what they came up with as a POSSIBLE issue:

Disconnect Remote Start as that might be causing these issues(haven't gotten to that yet).
Next possible issue if it happens again after disconnecting the remote start would be the Body Control Module going bad.
Lastly, the passkey could be going bad(but they said that is highly unlikely from the sounds of everything).

One other note: The following error codes came up at the 1st Chevrolet dealership when they put it on the computer: p0128, p0136, p0137, p0615, and p0703

So, could someone please help me out on what the issue could be? I can't keep throwing money on a guessing game.

Also, if it was to be the BCM, can I buy one myself and have my mechanic install it as Chevrolet wants $700+ to do it.

Thanks for your time,
Nick

Originally Posted by brettstoner

So you have a poor electrical connection somewhere, electrical component near the point of failure, or intermittent electrical short/open. First clue is everything works fine then the radio cuts out. The radio communicates on the Canbus so we don't know if the problem is being caused by the radio or the radio is on the receiving end of the problem. (The Canbus is the cars network where all the modules talk on, ie BCM, PCM, radio, SDM, TAC, DIC, IPC, HVAC, etc, OBD2 port).

Did the dealer do diagnostic work besides load testing the battery, measuring volt and amp output of the alternator, and cranking the car over attempting to duplicate the condition? Did they read live data to troubleshoot all the Powertrain codes? Did they attempt to pull any body, brake, or network codes? Did they check for battery voltage at the PCM and BCM? Did they measure the resistance of the grounds at the PCM and BCM?

You have lots of diagnostic work to do here. I would not throw parts at it but start checking everything. Start with the basics. We have a known good battery (fully charged) with clean corrosion free connections on all points of the battery cables. All fuses and relays are receiving 12v+ and operational. Hook up a scan tool and read live data. Can you read all sensor data and it makes sense? (Troubleshooting some of those powertrain codes, ie poor connection to PCM, PCM getting funky data from a bad sensor, PCM not getting 12+v or high resistance ground).

Your car is showing multiple problems....
1. Crank but no start. (Are fuel injectors getting 12+, is fuel pump priming, are fuel injectors getting grounded aka commanded to squirt fuel by the PCM, do you have spark while cranking)
2. Radio cuts out. (Check for 12+v on orange wire (B1 connector) hot at all times and purple wire (B3) ignition switched, good ground, is it getting or sending bad signals on the serial data line)
3. All the powertrain codes. (Are you getting good data from each sensor, troubleshoot each p code, are they related, all appeared at same time or developed over time but not addressed, poor ECM connection, etc)

You could have something as simple as a bad connection somewhere, a component reaching the point of failure, poor grounds or low voltage, or a bad component on the serial line sending bad data (I have seen a bad radio cause a no start condition but not common).

If you don't have the tools and experience to troubleshoot electrical problems I would call around to find an experienced diagnostic technician. It's easy to swap car parts. It's hard to troubleshoot intermittent electrical faults. They are worth the price.

Brett,

1st thing, I have absolutely no clue what they did and I'm not knowledgeable on anything you just said and it just confused me.

2nd, on your 1.(crank, but no start), you misunderstood what I said. It got NO CRANK(what it would get if the passkey was screwed up) after this happened. I don't have issues when it cranks as it starts right up, it just randomly does the no crank click after I get the radio cut out/service security system/service traction control messages.

Then on 2 I don't understand any of that either

Number 3, my local dealership said the first 2 could just be o2 sensor and thermostat going bad. The last 3 they said are connected to the BCM(starter relay switch and brake switch circuit) which makes them think the BCM is going bad. I will add one thing on the brake switch circuit....could that error code be coming up for when all my brake lines blew back in August and I had my mechanic replace everything and he didn't do a code check?

Originally Posted by brettstoner

So you have a poor electrical connection somewhere, electrical component near the point of failure, or intermittent electrical short/open. First clue is everything works fine then the radio cuts out. The radio communicates on the Canbus so we don't know if the problem is being caused by the radio or the radio is on the receiving end of the problem. (The Canbus is the cars network where all the modules talk on, ie BCM, PCM, radio, SDM, TAC, DIC, IPC, HVAC, etc, OBD2 port).

Did the dealer do diagnostic work besides load testing the battery, measuring volt and amp output of the alternator, and cranking the car over attempting to duplicate the condition? Did they read live data to troubleshoot all the Powertrain codes? Did they attempt to pull any body, brake, or network codes? Did they check for battery voltage at the PCM and BCM? Did they measure the resistance of the grounds at the PCM and BCM?

You have lots of diagnostic work to do here. I would not throw parts at it but start checking everything. Start with the basics. We have a known good battery (fully charged) with clean corrosion free connections on all points of the battery cables. All fuses and relays are receiving 12v+ and operational. Hook up a scan tool and read live data. Can you read all sensor data and it makes sense? (Troubleshooting some of those powertrain codes, ie poor connection to PCM, PCM getting funky data from a bad sensor, PCM not getting 12+v or high resistance ground).

Your car is showing multiple problems....
1. Crank but no start. (Are fuel injectors getting 12+, is fuel pump priming, are fuel injectors getting grounded aka commanded to squirt fuel by the PCM, do you have spark while cranking)
2. Radio cuts out. (Check for 12+v on orange wire (B1 connector) hot at all times and purple wire (B3) ignition switched, good ground, is it getting or sending bad signals on the serial data line)
3. All the powertrain codes. (Are you getting good data from each sensor, troubleshoot each p code, are they related, all appeared at same time or developed over time but not addressed, poor ECM connection, etc)

You could have something as simple as a bad connection somewhere, a component reaching the point of failure, poor grounds or low voltage, or a bad component on the serial line sending bad data (I have seen a bad radio cause a no start condition but not common).

If you don't have the tools and experience to troubleshoot electrical problems I would call around to find an experienced diagnostic technician. It's easy to swap car parts. It's hard to troubleshoot intermittent electrical faults. They are worth the price.

Okay...quick update, but still not figured out the issue. It happened again tonight and I took it straight to my guy at Advanced. The OBD2 port is definitely screwed up as well because the diagnostic tool they use can't read anything. So, he told me to take it to this local garage that the guy will not touch anything until he runs every possible test on every part.

Hopefully I can get this figured out finally because I can't take this driving and not knowing if I'm gonna be able to get home.

Originally Posted by Scottydoggs

power port fuse is blown, it also powers the obd2 port.

Would that cause all the issues like the radio and dash to stop working(that includes ALL gauges and the windshield speedometer....but they work later on...and now the car won't start, it just clicks again.

It is 100% not the starter, battery, or alternator as those have been tested twice and I never have issues with it starting until the computer starts going crazy. Also, no check engine light either. We are thinking it's either the BCM or the PCM.

Originally Posted by Scottydoggs

is this a aftermarket remote start you have that the dealer suggested to take out? those things can cause all sorts of issues if the wires were just cut twisted and taped up. id be checking all that out for sure

Yes it is. The remote start worked perfectly fine until I had the tumbler changed out, now it just tries to start 3 times(doesn't turn over or nothing, but gets further than the click with turning the key in the tumbler). I will say though it looks like it was very professionally installed from how the sensor is put in(top corner of windshield and all the wires hidden).

Originally Posted by Scottydoggs

was the key changed? some hi end remote starts need the key programmed to it.

Not that I know of...but it's definitely not a hi end remote start....I'm gonna take it to the guy I was suggested to tomorrow and hopefully get an answer finally.

Originally Posted by Scottydoggs

good luck. i hate gremlins.

Thanks...what irritates me the most is I had an 02 that was rusted out, hit 5 deer with(only thing I ever had to fix was a headlight) and just didn't look the greatest and I never threw 1 dime into it and everyone kept yelling at me for 2 years to get rid of it. So in Oct 14(it wouldn't pass inspection because of the rust in PA), I got this car and I've already had to put whole new exhaust system on it($250), brake lines blew out and I almost totaled it($500), and now this...which is so far $700.

Originally Posted by J57ltr

Couple of things:

The remote start you have, what brand is it, and is there another key hidden behind the dash to allow the system to start?

Was the remote start installed when the car was new, or did you have it installed after you bought the car?

You mention that the ignition switch was replaced and the remote start no longer worked after that. I am going to say that when the switch was replaced that the device was not reattached around the ignition switch so the car doesn't "see" a key therefore it won't start.

Back when I was installing we had a few methods to bypass anti theft systems on RFID style keys.

One was to take a customer key (typically a valet key) take a piece of wire and wind a few turns of wire around the key then take the other end and make a few wraps around the ignition switch, take the 2 loose ends and attach them to a relay that is active only when the remote start is active. This creates a way for the car to see the key even though it wasn't in the lock cylinder.

Two was a module that the key was placed into and closed and a loop that went around the ignition switch. Basically it was the same thing just in a tidier package.

Three was a module that was connected directly to the databus and would fool the car into thinking that there was a key present. These were higher dollor and back in the mid 2k's were about $40-$50 our cost and would typically add about $150 to the price of the alarm, but you got to keep a $75 key so some would go for that. (adults would kids didn't care they wanted the cheapest way they could get away with).


Do you have a aftermarket radio as well?

Jeff

Jeff, I can't answer any of your questions because I don't now the answer to any them, except no on the radio.

We have it down to the BCM being the problem according to my new mechanic as he's changed over 25 of them in the past few years. He can't get it on his machine until Monday though to give us the 100% diagnosis, but from the error codes I previously received, that is what I'm leaning heavily towards.

Update: Last week my mechanic checked the battery and it had a dead cell and only 10.6 volts. So we changed that and it still happened this past weekend.

Took it back and only codes coming up were data codes. Turns out, whoever installed the remote starter also installed a 2nd passkey system. My mechanic said he has seen and had to remove at least 30 of these systems and the issue has gone away. Some people shouldn't be allowed to install things into cars....