THis is on a 1984 Olds Cutlass with a computer controlled carb. It uses a version of the computer controlled QJet on the 3.8L V6 that's in the car (It's a Dual-Jet, the front half of a QJet).

Driving around the Choke/Oil light will come on at idle when warmed up. Engine runs fine in all respects, Diacom says all's right with the motor.

I know that this light coming on will often be due to a bad alternator but the voltage checks out fine- ~14.0V at idle. The choke mechanically seems to work fine, too- closing when cold, opening fully when warm. If I totally UNPLUG the wire to the choke element the Choke/Oil light goes OUT. I verified there is full +12V or more at the wire feeding the choke element, too. Odd.

I never did understand exactly how this circuit worked and what would make the light come on- could somebody fill me in, please?

 

I assume you have the "granny" instrument cluster with just a speedo and a fuel gauge... the wiring is very different b/t the two.

Anyhow, I've been looking at the circuit, and it's a clever design, to say the least.

As a guess, I'd say you may actually have low pressure. Buick motors are NOTORIOUS for oiling system problems... Either that or your oil pressure idiot switch is bad. The fact that it only happens at idle make me think you have an actual problem. Probably the oil pump gears have scored the cover and it cain't maintain any pressure when it's spinning slow. You might want to see if the problem goes away if you bump the idle speed up--or maybe it only comes on at idle in gear and not in park/neutral?

I'll take some pics of my service manual and post them in a second.

Oh and FYI, the alternator doesn't affect the way this light works as far as I know. It's wired quite differently than the thirdgen's.

 

 

 

Hawk- thank you so much. That's exactly what I needed. You're right- it's a granny-style instrument cluster with just speedo and fuel gagues. I really appreciate the diagnostic trees. I owe you one.

 

Hmmmmm.......

It's not really much of a Choke indicator is it? If the choke's unplugged the circuit will never ground and the bulb will never come on. Says absolutely nothing about the condition of the choke but agrees completely with my observations.

I see what you mean about it maybe boiling down to actual low oil pressure. There's no much more to go bad. Maybe replace the oil pressure sender in hopes that that's what's bad.

I'm definitely off on a mission now.

 

An unrelated side question- if I HAD gagues how would the circuit know if there was oil pressure? I don't see an oil pressure switch anywhere in the circuit diagram.

Emmmmmm.... nevermind. I guess the choke/oil light would function ONLY as a Choke light, seeing as how there's a separate gague for the oil pressure. Missing the forest for the trees. Right?

 

No problem man, you've helped me enough times

And yes, I imagine if you had gauges, the choke/Oil light would be for the choke only, if you had a Buick V6 with gauges. I'm only guessing because I've never seen a V6 with gauges--only V8s.

The Olds V8s (only V8 in Olds and Buick) never used an electric choke, so those used the choke/oil light as an oil light only, unless you had gauges, in which case the bulb isn't there at all and the light doesn't function.

As far as the "choke" light function, if it is unplugged, the light is never on. I imagine you're supposed to notice that the light is out when it should be on (key on, engine not running) and wonder what's going on.

What's odd, is if you disassemble the cluster, you can see there are TWO "Temp" lights and TWO "Fasten Belts" lights--yet they decided to combine the oil and choke light into one for no apparent reason.

I think it boils down, once again, to the fact that cocaine was popular in the 80s.

 

Heh heh heh. Yeah, no kidding. I hear that. Thanks again.