I have a 87 Camaro Sport Coupe with the LG4, and the stock carb. lately I have been getting the choke light on and off. I did a search and everybody says it is a bad Alt. I have checked the alt, and it is working fine. Today the choke is not opening I checked voltage at the choke, and I only get 4.5 volts. The Alt is putting out 14.5 volts. Anybody have any idea why I would begetting such low voltage the the choke?

 

I have been looking at the factory service manual i have, and I noticed there is a choke heater relay. any idea on where that may be located?

 

It is entirely possible for the alt to appear to put out 14.5V, but still not be charging 1/3 of the time.

If the "Alt" light, labeled "Choke", comes on, then the alt is not working right. And if the alt isn't right, the choke won't work right either.

The choke heater relay is under the dash, in the "convenience center". The ALDL plug is located on the front edge of this "center". But it doesn't matter where that is; you need an alternator.

 

Yeah, probably the alternator, despite what you're seeing, but before you replace it, yank the field coil plug on the side of the alt (the 2-wire blade connector) and see if the terminals are corroded. I just chased one a couple months ago where the alt wasn't doing it's job and I found (AFTER a new alt didn't fix it) that the stupid terminals were all futzed up. Cleaned, reinstalled and it charged up like a dream with both the new and old alternators.

Doing the same check on the choke heater wire connector is probably a good idea, too. 90% of the time that single-wire connector is smashed or mangled in some way by a PO. Not beyond the realm of possibility that corrosion could happen there as well. Like the alternator field coil connector, it's not a sealed connector.

 

So i figured I'd give an update on this. I have changed the Alt. and it did not fix the choke problem. The light came on last night, and would not turn off no mater what I did. The choke was starting to close sending the engine into fast idle. I don't know how many of y'all have looked at the circuit for the choke but it is interesting. The choke heater relay is energized by the oil pressure switch. which then sends power to the choke. the light is also tied directly into this circuit not in any way tied in to the alt wiring. (according to the factory service manual printed in 1987 by Chevy). I'm going to change the pressure switch and get back with y'all. And the heater relay was mounted on the left side of the firewall between the fan relay and the map sensor. at least on my 1987 model. thanks for your time and i will keep y'all updated.

 

Make sure that you are indeed looking at the relay and switch for the choke. That two wire OPS and relay control the in-tank pump on my 87 LG4. I've verified this by jumping that relay to check fuel pump function. Choke heater relay is under the dash somewhere on mine.

 

I looked under the dash and when I unplugged what I thought to be the relay for the choke I still had voltage going at the choke. (it started working by time I was able to look at it) found the relay on the firewall, and had continuity from the choke wire to that relay. And the orange w/white tracer and Tan wire coming from the OPS was also on that relay excatly like the FSM wiring diagram. Plus my hypothesis is based on every time I have to brake hard the oil pressure drops, and the choke light comes on. Been doing this for 13 years cause the oil pan is crushed from the PO never have any oil problems other than that just something i'm used to seeing. Which is exactly what happened last night cause some idiot cut me off, and then came to a stop. OP dropped and the choke light came on OP came back ,but light stayed on never going out then the idle started picking up which told me the choke was closing. Just got a new switch, and a choke plug since the one I have is not the best but it is making connection. I'm going to change them tomorrow at work and see what happens.

 

OK update as promised. I have changed the oil pressure switch. The light was on before I changed it, and went off after it was changed. I drove it for 2 days to and from work, and the light has stayed off. The choke is working properly even better in fact. it comes out of high idle faster now. Thanks for you time, and I hope this thread will help any one else in the future

 

Can anyone show me a wiring diagram where it shows the oil pressure switch wired together with the choke? I have looked at the diagram for my 1985 Firebird (VIN H). It doesn't look like it is wired in with the oil switch. My problem is, I have 12 volts at the wire connector and at the choke relay terminal when choke is not connected. When connected the relay terminal (light blue wires) still show 12 volts, but I only get 5 at the choke terminal connector.

Does this sound like a voltage drop issue? The choke heats up and operates normally when hooked up directly to power, but not when hooked up on the car. Does the car have to be running for it to work, or is ok to just have in the run position?

 

Choke should be wired so as to only receive power when the alternator is spinning.