QuestionAny suggestions on where to look for the ground related to these systems and how to get to it?
Thanks... garycox@netten.net
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Followup To
Question -
1997 Pontiac Grand Prix 2.8 ltr v6 engine. 104,000 miles.
The problem started out where the air conditioning/heating blower motor would cut off for a few
seconds and then back on. It started to become progressivly worse happening more often and
for longer duration.
Also when the blower motor cut off the led for the airconditioning would also go off as well as
the led for the rear window defogger. The running lights would also go off. Also when this
electrical outage occurred if the headlights were turned on by the automatic daylight sensor they
would turn off but if I manually had the headlights on by the manual headlight switch the
headlights would stay on.
The radio and engine were not effected by the electrical outages. I could also hear a click in the
dashboard when the electrical outage would occur and a click when it would come back on as if a
relay was tripping.
The problem has progressed to where 95% of the time that the airconditioning/heater blower
motor and the above mentioned electrical systems do not function at all if I have the blower set
on speeds 1-4. If I set the blower to speed 5 the blower consistantly works as well as all
electrical systems. As soon as I turn the blower to setting 1, 2, 3 or 4 the blower moter turns off,
I hear a click in the dashboard, the running lights turn off, rear window defogger does not work
and the airconditioning light goes off (the airconditioning compressor also cuts off). As soon as I
turn the blower switch to off or to posisition 5 everything comes back on. Of course, in off
posisition the blower moter does not run normally but all other electrical systems are
functioning.
The dealer checked the computer and it did not have any codes for any problem. The battery has
been replaced.
Gigling the blower switch or switching it between speeds 1-4 does not effect the problem as the
effected electrical systems will remain dead.
While this may or may not be related the gas gauge does not consistantly work. Often it will
show all the way full no matter how much gas is in the tank. Sometimes it will show the correct
amount of gas but when it isn't working it always shows full.
As I mentioned the Radio and engine has never been effected by the electrical outages.
It sounds like to me like a protection circuit activating like a circuit breaker and that the running
lights, blower motor, rear window defogger and airconditioning are on the same circuit?
Perhaps it is a short or a grounding problem? I'm not a mechanic, I'm a computer tech so I'm not
sure where to check for electrical connections or grounds if that is what I should be checking for?
Any ideas would be appreciated as no one else has any? The common element is the effected
electrical systems with the blower switch being the catalyst that causes it all.
Answer -
It sounds like a ground problem to me. I dont have any wiring diagrams for this car here at home
but I will check into it tomorrow at work. If you could respond back to me with a follow up
question, I will have some info for you.
You have to respond back or your question will be lost and I wont be able to help.
By the way, thanks for all of the info. It will help me to find your problem.
AnswerHi, sorry its taken so long for me to get back to you but I think I know the cause of your problem now. I traced every circuit that you said has the problem and also the ones that dont. The grounds are not related in any way. The power feeds are though. Everything that you are having a problem with traces back to the DIC/HVAC fuse which is fed directly from the ignition switch. The high speed blower runs off of the HVAC HI fuse.
Ok now here is the problem, all of the circuits that fail are running off of the same feed out of the ignition switch. The other feeds out of the ign. switch are the ones that are still working. We have had alot of problems with the ignition switches on these cars but not with the problem that you are having but I am sure that this is your problem. If you want to check it to be sure, you can check for a loss of power to the DIC/HVAC fuse (in the dash fuse panel) when the problem is happening.
