Gain extra benefits by becoming a Supporting Member Click here find out how!
Classic Performance Products Classic Parts
Ciadella InteriorsAmerican Auto Wire Classic Industries
Chevs of the 40sDanchuk Catalog
Hellwig Products IncPerformance Rod & CustomEcklers AutoMotive
Nu-Relics Power Windows
Impala Bob's Bob's Chevy Trucks Bob's Chevelle Parts Bob's Classic Chevy

Username Post: 81 C10 choke light        (Topic#243925)
Posts: 81

Loc: Shreveport, La.
Reg: 02-01-04
06-16-10 11:23 AM - Post#1931154    

I've got an 81 C10 that originally came with an electronically controlled 2-barrel 305. Its got an earlier model 350 with a quadrajet on it now, so there's lots of wires running around that don't go to anything. I'm eventually going to rewire the whole thing, but I need to keep driving it in the meantime. One of the issues I'm having is that the choke light in the dash either stays on or flickers, which can be really annoying, especially at night. The choke itself was zip-tied open when I got the truck, and since I could't figure out where it was supposed to be wired in originally, I spliced it into the switched power from the alternator, and everything worked fine. The light didn't start coming on until a couple months after that. The main problem I'm having with troubleshooting, is that the wiring diagram I have in my repair manual (chilton) doesn't really make sense when it comes to the choke. It shows the choke getting its power from the oil pressure sensor, but also says that setup is "V6 only" but doesn't show the V8 alternative. It also doesn't show any choke indicator light at all. Anybody have a more complete wiring diagram, or some helpful suggestions to run this thing down?

I Fish 
Posts: 135
I Fish
Loc: NJ & MD
Reg: 10-29-09
06-16-10 12:02 PM - Post#1931169    
    In response to Carl_Cash

not sure, but i seem to remember reading somewhere that the choke lights on these vintage acted like a "check engine light" as well. You might have some other issue that is causing it to flicker. i'm sure one of the guru's here will be much more helpful

Posts: 383

Loc: Dallas, TX.
Reg: 11-10-03
06-16-10 01:46 PM - Post#1931212    
    In response to I Fish

There is also a oil pressure switch with 2 prongs back near the distributor (assuming your truck had the V8 from the factory) that sends power to the the choke wire at the carb when there is enough oil pressure with the engine running. That switch may be disconnected, damaged or missing. I jumpered that connector on my 86 and fixed my choke problems.

Sounds like you have replaced the factory wiring. Could the original choke wire be shorting out or not connected? I think the Choke light will turn on if the wire is disconnected or does not have the correct electrical load or resistance on it.

Edited by Dale_Holley on 06-16-10 01:50 PM. Reason for edit: added info

Posts: 81

Loc: Shreveport, La.
Reg: 02-01-04
06-17-10 01:24 AM - Post#1931598    
    In response to Dale_Holley

The oil pressure sensor currently on there only has one plug, probably because the engine is out of a 70 model pickup (according to the block number; I've only had the truck a couple months, God knows WHAT all was done to it before I got it). I tried splicing the choke into the wire at the sensor, but it killed the signal to my pressure guage. Thats when I ended up splicing it into the switched power from the alternator. What you say about the light coming on if the choke isn't getting power makes sense, but the light didn't start coming on until a month or so after I wired the choke up my way.

"15th Year" Gold Supporting Member
Posts: 18770
Loc: Colorado Springs, CO
Reg: 08-08-04
06-17-10 09:06 AM - Post#1931712    
    In response to Carl_Cash

It's not a particularly good idea to wire up the electric choke to either the alternator turn-on wire or the ignition. If wired to the ignition, it can cause the HEI to fail unexpectedly, if wired to the alternator field, the battery may not charge reliably. The electric choke draws A LOT OF POWER - like 20 amps - and you don't want to hook up that kind of current draw to either of these sources.

If you want to use either of these key-on power sources, it is best to isolate the current draw from them by using a relay. Relays are electrically activated high power electrical switches - allowing you to hook up straight battery supply power to whatever you are trying to power, but turn it on using very little current (and therefore won't impact the key on power sources in the engine bay).

If you are rooting around the engine bay trying to find the original choke circuit - it will be at least 12 gauge in size, and should only have power to it during a cold start, key-on.

IF the light is coming on, you may be grounding the choke wire in some fashion. This would be bad, generally speaking. I would do my best to find it, and fix it promptly.

Posts: 81

Loc: Shreveport, La.
Reg: 02-01-04
06-17-10 09:06 PM - Post#1932032    
    In response to Vaughn

Hmmm, so is that how it was originally wired? With a relay activated by the oil pressure sending unit? That actually makes sense, but its still odd that the wiring diagrams don't show a choke circuit. My fuse box even has a 20 amp fuse labeled "choke", and the fuse box diagram on the wire diagram shows it too, but no actual circuit to go with it. I suppose I could always pull the box loose and trace down the wires that attach to that fuse. Lol, judging by the rest of the wiring "repairs" done to this truck, its probably powering the windshield wipers or something.

Forum Newbie
Posts: 2

Reg: 12-06-10
12-06-10 02:03 PM - Post#2014346    
    In response to Vaughn

I'm probably going about this wrong, new to forum, but I have a 84 C10 that has this choke light, but my problem is that I have the wiring diagram that shows a light blue wire coming from the choke to a ???? box where a dark blue wire comes off of to the oil switch and a pink/white wire that runs to the fuse box. I thought this box was a choke relay but no parts house show a choke relay. I can't find this ???? box With the switch on the choke light is lit but as soon as engine starts it will stay on a second and then blow the fuse. I put a new oil switch on and connection at the choke is good, so problem must be at box I can't find. Do you know what this box ???? is called so I can buy one to see what the darn thing looks like? Any help will be appreciated. Steve

Subject Matter Expert - Senior Member
Posts: 3743
Loc: Twin Cities, Minnesota, U...
Reg: 04-25-04
12-06-10 03:27 PM - Post#2014370    
    In response to Carl_Cash

Here is a link to how it is wired on a 1984 Camaro:

I should have a truck link too but can’t find it at the moment.

I have discussed this topic somewhere here at Chevytalk in the past if you went to try a search.

For those of you that are wondering why you are not getting replies to your thread:

Did you give the model, year, engine, fuel system type, and transmission information?

If your vehicle has been altered from stock, let us know about that too.

Senior Chevytalk Moderator
Posts: 24297
Loc: Austin, TX 78748
Reg: 05-09-00
12-06-10 06:29 PM - Post#2014429    
    In response to Chevytech

Welcome to the site.
You can find complete diagrams at

Compliments of Captkaos.

'95 Jimmy SLT (Bought @131,814)
'83 Silverardo XST - ZZ4 powered
'96 GMC Jimmy LS Ret. @236651 miles

Icon Legend Permissions Topic Options
Report Post

Quote Post

Quick Reply

Print Topic

Email Topic

FusionBB™ Version 2.1
©2003-2006 InteractivePHP, Inc.
Execution time: 0.454 seconds.   Total Queries: 13   Zlib Compression is on.
All times are (GMT -0800) Pacific. Current time is 09:48 PM