Need Help!!

[PontiacGrandAmGT]

Okay, so I have a 2002 Pontiac Grand Am GT. I have a problem with the headunit. It will not turn on but it does have power. I hooked up the stock headunit and it had power but didn't work. My after market just stopped working. Checked all the fuses and everything. They are all good. This is the first problem.

Second problem, I drove home then hopped back into the car to go to the gas station. The "Service Vehicle Soon" light came on. And the dash/AC lights wont come on. All the interior lights don't come on. I cannot figure it out. Anyone can give some input?

 

[oldhippie]

Okay, so I have a 2002 Pontiac Grand Am GT. I have a problem with the headunit. It will not turn on but it does have power. I hooked up the stock headunit and it had power but didn't work. My after market just stopped working. Checked all the fuses and everything. They are all good. This is the first problem.

Second problem, I drove home then hopped back into the car to go to the gas station. The "Service Vehicle Soon" light came on. And the dash/AC lights wont come on. All the interior lights don't come on. I cannot figure it out. Anyone can give some input?

For the radio: I take it you've checked both fuses associated with the radio. Should be one that is powered directly from the battery in the right side I/P junction block and the one powered through the ignition switch located in the left side I/P junction block.

The interior lighting is controlled through the Body Control Module (BCM). If you have a OBD II code reader, read the code. I suspect it'll direct you to the BCM.

One thing in common with your problem is the ignition. How loose is your key when you put it in the ignition? If it is sloppy or requires a little finessing to turn, then your ignition lock cylinder or your key could be worn out. This will affect the BCM.

 

[oldhippie]

Was the stock unit an anti-theft (Theftlock audio system)? When it was removed was the anti-theft feature disabled before the power was disconnected? If the power was disconnected w/o disabling the anti-theft, the stereo will remain inoperable even if power is restored.
There is a procedure to unlock the stereo after a power loss. Check your owner's manual.

 

[PontiacGrandAmGT]

For the radio: I take it you've checked both fuses associated with the radio. Should be one that is powered directly from the battery in the right side I/P junction block and the one powered through the ignition switch located in the left side I/P junction block.

The interior lighting is controlled through the Body Control Module (BCM). If you have a OBD II code reader, read the code. I suspect it'll direct you to the BCM.

One thing in common with your problem is the ignition. How loose is your key when you put it in the ignition? If it is sloppy or requires a little finessing to turn, then your ignition lock cylinder or your key could be worn out. This will affect the BCM.

Thanks. I checked both of the fuses and they were good. But I didn't check the BCM for the interior lights. The key isn't very lose so it should be okay... But now when I connect the stock head unit I get no power at all. The lights don't even come on... Does the BCM have anything to do with that?

______________________________

 

[oldhippie]

Thanks. I checked both of the fuses and they were good. But I didn't check the BCM for the interior lights. The key isn't very lose so it should be okay... But now when I connect the stock head unit I get no power at all. The lights don't even come on... Does the BCM have anything to do with that?

Do you have a voltmeter or multimeter to check voltage with?

My Hayne's repair manual covers '98 to 2003 Grand Ams and it only shows one schematic for the audio. There is the VSS that is fed from the BCM but I'll have to look closer at the schematics again when I get a chance.

Do you have a spare key for the car that's still like new? Could try that one and see if it's less loose. Mind you when my key was that loose I was also getting the security light coming on almost constantly and when I used my seldom used spare the problems decreased in occurance.

 

[oldhippie]

Thanks. I checked both of the fuses and they were good. But I didn't check the BCM for the interior lights. The key isn't very lose so it should be okay... But now when I connect the stock head unit I get no power at all. The lights don't even come on... Does the BCM have anything to do with that?

Looking at the factory repair manual for my '07 G5, and knowing our 2002 G Ams also have the retained accessory power, I'd have to say yes, the BCM does control the radio, along with the power windows, instrument cluster and interior lights.

 

[PontiacGrandAmGT]

Looking at the factory repair manual for my '07 G5, and knowing our 2002 G Ams also have the retained accessory power, I'd have to say yes, the BCM does control the radio, along with the power windows, instrument cluster and interior lights.

Okay. But if BCM controls the power windows plus instrument cluster wouldn't it affect those as well if the fuse was blown? Just not the accessory power and interior lights? ... How would I get the BCM checked out???

 

[oldhippie]

Okay. But if BCM controls the power windows plus instrument cluster wouldn't it affect those as well if the fuse was blown? Just not the accessory power and interior lights? ... How would I get the BCM checked out???

If the main fuse to the BCM was blown, then I believe none of the things controlled by it would work.
If I under stand the BCM correctly, its internals are like several relays. There is the main fused supply to the radio, for example, but the controls in the BCM will act to energize the 'relay' to complete the circuit to the radio. Much like your fuel pump, you have the main fused supply to the pump relay but the signal to energize the relay and complete the circuit to the pump comes from the PCM. As I've found out, a low voltage will fail to operate the relay and pump motor.

I have no idea how to test the BCM, but I'd first make sure there is battery voltage at the radio connection in Acc and Run modes. If the voltage is low, this would indicate a high resistance (possibly a ground) in the circuit. If voltage is nonexistant that may indicate a faulty BCM. I am by no means an expert on this.

______________________________

 

[oldhippie]

Okay, so I have a 2002 Pontiac Grand Am GT. I have a problem with the headunit. It will not turn on but it does have power. I hooked up the stock headunit and it had power but didn't work. My after market just stopped working. Checked all the fuses and everything. They are all good. This is the first problem.

Second problem, I drove home then hopped back into the car to go to the gas station. The "Service Vehicle Soon" light came on. And the dash/AC lights wont come on. All the interior lights don't come on. I cannot figure it out. Anyone can give some input?

For the head unit: did you check your ground connection?
Does the car still start and run OK and with all instrument values working?

 

[PontiacGrandAmGT]

For the head unit: did you check your ground connection?
Does the car still start and run OK and with all instrument values working?

The car starts right up. Runs like a dream besides getting a little hot. I noticed that my dimmer switch doesn't work. So that may be faulty... But when I turn it on the bottom light above the brake pedals and passenger work. My light on the ceiling works as well. But the dash lights and the radio do no work. My ground is set good. But I know when my cousin decided to hook up the LED lights under my car he tried to run the behind the head unit using those wires and he touched the ground wire from LED to the other ground and it created a spark. And that's when my fuses blowed. So I fixed those. I forgot to mention that.

 

[oldhippie]

The car starts right up. Runs like a dream besides getting a little hot. I noticed that my dimmer switch doesn't work. So that may be faulty... But when I turn it on the bottom light above the brake pedals and passenger work. My light on the ceiling works as well. But the dash lights and the radio do no work. My ground is set good. But I know when my cousin decided to hook up the LED lights under my car he tried to run the behind the head unit using those wires and he touched the ground wire from LED to the other ground and it created a spark. And that's when my fuses blowed. So I fixed those. I forgot to mention that.

Your cousin is a good example of why all repair manuals state to disconnect the negative battery cable before working on electrical circuits. Something you can definitely raz him on..

That's definitely a tidbit of information that helps to know when troubleshooting.
Which fuses blew?
And do you have a multimeter or voltmeter?

 

[oldhippie]

I noticed that my dimmer switch doesn't work. So that may be faulty... But when I turn it on the bottom light above the brake pedals and passenger work. My light on the ceiling works as well. But the dash lights and the radio do no work.

Looked at some schematics again. The interior lights, the bottom lights ie interior courtesy lamps, dome, reading and vanity lamps power supply is from the 10 amp Int Lamps fuse in the right instrument panel junction block but control is through the BCM.

The instrument lamps which includes the radio, tranny shift indicator, ashtray, heater/A/C control and instrument cluster lamps power supply is from a 10 amp fuse also located in the right I/P junction block.
The dimmer switch controls these lamps but when you rotate the switch all the way it picks up seperate contacts for the interior lamps.

Did you also replace the Inst Lamps fuse? Its at the top right hand corner of the right I/P junction block.

______________________________

 

[PontiacGrandAmGT]

So I fixed the head unit... But I noticed that with the dash lights, my tailights do not work. The runner lights don't work but the brake and blinker lights on the tailights work... So I am thinking that it may be the altenator? Or just blown tailights?

 

[oldhippie]

So I fixed the head unit... But I noticed that with the dash lights, my tailights do not work. The runner lights don't work but the brake and blinker lights on the tailights work... So I am thinking that it may be the altenator? Or just blown tailights?

The alternator won't affect your taillights; it'll affect the battery charge. Check the bulbs first.