1988 Supreme Classic Power -Wiring Headaches
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Joined: Jun 2015
Posts: 156
1988 Supreme Classic Power -Wiring Headaches
Hey out there who are G-body guys. Now on my 5th Cutlass 79 H/0 - 80 442 - 86 442 - 88 Supreme Classic - now another 88 Supreme Classic
I've run across something I JUST CAN'T FIGURE OUT. Not that I'm a mechanic or wiring guy cause I'm not.
I bought a 1 owner - 80,000 mile vehicle that has been parked since 2009. Owner said his son drove it, gave it back, was running good when
parked and the man is older, was going to tinker with but never did. This car is loaded with every option plus T-Top.
Motor turns over, oil is good, even radiator good. But HERE'S THE ISSUES. Put a battery it ------
LIGHTS WORKING - interior sail panel - dash - radio - tail lights - side marker lights - side corner header panel lights - even under the hood light - both power windows work
DOESN'T WORK - Headlights - Turn signal's won't blink- and why in the world does POWER SEAT DOES'NT WORK.
It' weird so many lights work but headlights don't - maybe the flasher for turn signals.
Wiring looks awesome and nobody's boogered with them.
EVERY FUSE in fuse box is perfect
Anyone have any suggestions? Thanks for anybody's time.
I've run across something I JUST CAN'T FIGURE OUT. Not that I'm a mechanic or wiring guy cause I'm not.
I bought a 1 owner - 80,000 mile vehicle that has been parked since 2009. Owner said his son drove it, gave it back, was running good when
parked and the man is older, was going to tinker with but never did. This car is loaded with every option plus T-Top.
Motor turns over, oil is good, even radiator good. But HERE'S THE ISSUES. Put a battery it ------
LIGHTS WORKING - interior sail panel - dash - radio - tail lights - side marker lights - side corner header panel lights - even under the hood light - both power windows work
DOESN'T WORK - Headlights - Turn signal's won't blink- and why in the world does POWER SEAT DOES'NT WORK.
It' weird so many lights work but headlights don't - maybe the flasher for turn signals.
Wiring looks awesome and nobody's boogered with them.
EVERY FUSE in fuse box is perfect
Anyone have any suggestions? Thanks for anybody's time.
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Joined: Jan 2010
Posts: 2,546
Do you have a CSM wiring diagram for this? That should be stop #1. Check EVERY electrical circuit for operation. Check to see what works and what doesn't. You have a partial list so far.
Here's one on ebay. About $10 shipped including tax. NO reason not to have this and own an 88 G-body with their wiring mysteries.
1988 Oldsmobile Cutlass Supreme Chassis Service Manual | eBay
Power seat comes off a circuit breaker in the fuse panel. There's two. The lower one. No fuse. Defogger and door lock relay are in the same circuit.
I initially thought of fusible link with the headlights, but then again, it would affect taillights too. Check your cigarette lighter. It's powered initially from the fusible link going to the lamps.
What about wipers? door locks? Under dash footwell courtesy lights? Assuming your car has RPO TR9. Look at SPID sticker in trunk for RPOs. Parking and side marker lamps all work?
The issues you have seem to point to potential steering column stuff for the most part. Potentially the headlamp switch as well. Park switch turns on marker lamps and tails, but headlamps are on a separate but tied-in switch to the park lamps. No turn signals and no headlights (power goes through dimmer switch- do you have high beam indicator on dash when you click it to high beam? It comes off an offshoot of the power to the high beam bulbs. If you have light but no high beam, then there's something going on at the component level perhaps.
Here's one on ebay. About $10 shipped including tax. NO reason not to have this and own an 88 G-body with their wiring mysteries.
1988 Oldsmobile Cutlass Supreme Chassis Service Manual | eBay
Power seat comes off a circuit breaker in the fuse panel. There's two. The lower one. No fuse. Defogger and door lock relay are in the same circuit.
I initially thought of fusible link with the headlights, but then again, it would affect taillights too. Check your cigarette lighter. It's powered initially from the fusible link going to the lamps.
What about wipers? door locks? Under dash footwell courtesy lights? Assuming your car has RPO TR9. Look at SPID sticker in trunk for RPOs. Parking and side marker lamps all work?
The issues you have seem to point to potential steering column stuff for the most part. Potentially the headlamp switch as well. Park switch turns on marker lamps and tails, but headlamps are on a separate but tied-in switch to the park lamps. No turn signals and no headlights (power goes through dimmer switch- do you have high beam indicator on dash when you click it to high beam? It comes off an offshoot of the power to the high beam bulbs. If you have light but no high beam, then there's something going on at the component level perhaps.
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Joined: Jun 2015
Posts: 156
Hey guys, here's the skinny.
All lights now working except headlights, BUT headlights do work to some degree
I was working on car - the hood was up about 3 inches but still latched
Lights came on. Put my hand on the release lever - light went out and more so when started lifting the hood.
Let hood down in latch lights came on - back and forth when I slightly lifted hood. WHAT THE??
I touched wires everywhere when hood was up trying to find short. I'M BAFFLED
All lights now working except headlights, BUT headlights do work to some degree
I was working on car - the hood was up about 3 inches but still latched
Lights came on. Put my hand on the release lever - light went out and more so when started lifting the hood.
Let hood down in latch lights came on - back and forth when I slightly lifted hood. WHAT THE??
I touched wires everywhere when hood was up trying to find short. I'M BAFFLED
Registered User
Joined: Jan 2010
Posts: 2,546
Spitballing here:
Sounds like it's a potential GROUND problem? It's weird since the RH and LH headlamps are grounded in separate locations. I have an 87 CSM, but it's likely the same as 88 as they share the same headlamps. G102 and G103 are the grounding locations. They're located, per the CSM description (no diagram supplied), behind the respective side's headlamps. Which means they are bolted to the radiator support. RH is black/white and LH is simply all black. Look up under the radiator support front lip right where the headlamp wiring goes through the openings at the top on each side and you'll see the ground lugs/bolt. Get out your voltmeter and start checking that circuit.
It's quite possible that those wires aren't getting good connection. Not saying this is your issue, but it sure sounds like a connection issue when you open and close the hood. Since you say your underhood lamp works, it grounds through the hood so you know the hood is grounded.
May be that somehow the radiator support grounds through the hood hook? Highly improbable, but G-body wiring leaves a lot to be desired.
Sounds like it's a potential GROUND problem? It's weird since the RH and LH headlamps are grounded in separate locations. I have an 87 CSM, but it's likely the same as 88 as they share the same headlamps. G102 and G103 are the grounding locations. They're located, per the CSM description (no diagram supplied), behind the respective side's headlamps. Which means they are bolted to the radiator support. RH is black/white and LH is simply all black. Look up under the radiator support front lip right where the headlamp wiring goes through the openings at the top on each side and you'll see the ground lugs/bolt. Get out your voltmeter and start checking that circuit.
It's quite possible that those wires aren't getting good connection. Not saying this is your issue, but it sure sounds like a connection issue when you open and close the hood. Since you say your underhood lamp works, it grounds through the hood so you know the hood is grounded.
May be that somehow the radiator support grounds through the hood hook? Highly improbable, but G-body wiring leaves a lot to be desired.
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