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Help! by Nilknarf
Started on: 01-28-2008 07:57 PM
Replies: 3
Last post by: StockGT on 01-29-2008 01:53 PM
Nilknarf
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From: Bristol, IL, USA
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Report this Post01-28-2008 07:57 PM Click Here to See the Profile for NilknarfSend a Private Message to NilknarfDirect Link to This Post
I just bought my first Fiero and brought it home Jan 1st. It is a 1988 GT Black 5 speed, P/W, P/D, rear defrost and the original premium sound system (Missing the subwoofer setup but has the bass control on the roof console) 89,000 miles on the car original 2.8 motor and 5 speed trans. Everything works as it should as far as I know however I can't get the "Pontiac" on the rear to light up and my 3rd brake light will not work either.

Here's what I have tried so far with no luck for the 3rd brake light. 1) replaced the bulb. 2)Checked all the fuses except for the 2 big metal 30 amp ones on the side of the fuse panel (I don't think those are for this or am I wrong?). My brake lights, turn signals, headlights, sidemarkers, and reverse lights all work correctly. I checked under the engine compartment and there are 2 grounds, one from battery neg to engine block (they used 4guage copper wire, and from tranny mount to decklid (they also used 4 guage copper wire for ground). Neither of these grounds has any corrosion on them and are nice and snug on the grounding points. I don't know what else to look for on this.

What I tried for the "Pontiac" on the rear tail light assembly... 1) Changed all 4 bulbs with the correct size (194) 2) Checked all the fuses in the car.

The car has been in Illinois its entire life however the prevoius owner told me it has never been driven in snow or salt. The under carriage backs this up as there is no rust on this car's undercarriage. I don't know where I am going wrong with this. Help Please!!!!!

[This message has been edited by Nilknarf (edited 01-28-2008).]

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Hudini
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Report this Post01-28-2008 08:27 PM Click Here to See the Profile for HudiniClick Here to Email HudiniSend a Private Message to HudiniDirect Link to This Post
Do you have a multimeter? I would start at the brake switch and see if you have 12v coming into the brake switch on the orange wire. If yes, then check for 12v out of the lite blue wire (with brakes applied). If yes, then test at the socket using part of the metal frame for a ground. If no juice on the lite blue with brakes applied then it would indicate a bad brake switch. My '86 FSM shows the high stop light power comes directly off the switch on the lite blue wire. If everything checks out ok, then it has to be a bad ground after the light socket. Here is the wiring diagram I'm looking at. I apologize if the '86 and '88 differ. Anyone know if they changed things in '88?
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Report this Post01-28-2008 09:12 PM Click Here to See the Profile for HudiniClick Here to Email HudiniSend a Private Message to HudiniDirect Link to This Post
For the "Pontiac" lights. According to the '86 FSM, the lights should be on anytime the key is in the RUN position. Power is supplied through the FAN E fuse on the top right of the fuse panel. Power goes to the C500 terminal which is the big terminal back by your battery. After the C500 the rear tail light harness goes up under the right rear quarter panel between the frame rail and the outside skin. If you remove the right rear wheel well liner you will see it attached to the frame rail. There is a ground up on the frame rail too. This has been known to rust out.

The ground for the lights is called the G400. The FSM says it is located in the "right rear engine compartment". Frankly, I don't know where that is yet. Anyone know which ground the G400 is? (No one has told me if the '88 is that much different than the '86 either)

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StockGT
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Report this Post01-29-2008 01:53 PM Click Here to See the Profile for StockGTClick Here to Email StockGTSend a Private Message to StockGTDirect Link to This Post
Hudni - Looking at the 1988 Factory Service Manual the diagrams look the same with only a few minor differences.
Ground location for High level stop light - G201, Behind center of IP (Instrument Panel).

GT Emblem lights:
Power feed to lights -wire color is Brn/Wht in 88 FSM.
Wire diagram shows one common ground tie point - S407, location- Rear lights harness, behind RH stop lights.
Ground G202 location- Between seats, near rear bulkhead ( under center console ?)
No Engine Blower Relay on 88's.
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