73-87chevytrucks.com

73-87 Chevy _ GMC Trucks => Interior & Equipment => Instrumentation => Topic started by: danny_lancaster on October 15, 2019, 04:09:29 pm

Title: Location of temp gauge wire from the firewall to the sender?
Post by: danny_lancaster on October 15, 2019, 04:09:29 pm

Hello,

I have a 1981 Chevrolet Silverado C20 that I am trying to get the temp gauge to work on.  When I bought it, it didn't run so I have gotten it going.  It was all original. 

I replaced the sender, but the wire that was hooked up to it was black and didn't look right to me.  I unplugged it, tested it for voltage, it was at zero.  I found a loose green wire flopping around, hooked it up, but nothing.

At that point with me screwing around with it, I popped the needle off of the gauge.  I replaced it with a known working one.

I still have nothing on the gauge.  Since I replaced the head gaskets and stuff, I really want to know where the gauge wire comes from the firewall so I can trace it out.  I don't see colors very well so I can tell if something is greenish or reddish, but browns, reds, and oranges and different types of green are hard for me to spot.

The wiring and everything doesn't look butchered up, and it all looks factory to me. 

Truck is 1981 Chevrolet C20 Silverado with original 5.7 350 4 bolt main L series, original intake and carb, TH350 Tranny

Thanks,

Danny

Title: Re: Location of temp gauge wire from the firewall to the sender?
Post by: bd on October 15, 2019, 09:03:59 pm

The factory color for the temperature sender wire is dark green.  On the simplified diagram below, the dark green wire is marked 35(HXL); 35 is the circuit number, (HXL) is the type of wire insulation. 

The diagram illustrates where circuit 35 enters the firewall bulkhead connector.  The bulkhead connector is imaged from the driver seat or terminal side.  The "top" of the connector, when it is plugged into the firewall bulkhead, is on the left.  The dark green wire should run from the bulkhead connector to the driver's side rear of the engine.  From there it should run along the base of the valve cover nestled against the intake manifold and then drop down over the top of the valve cover to the temperature sender located between the #1 and #3 spark plugs.  If necessary, wipe the wire insulation with a rag moistened with aerosol brake or carburetor cleaner to more clearly identify its color.

Does the temperature gauge respond at all when the ignition is switched on?  Where is the needle pointing?  Do the other gauges work correctly?

Title: Re: Location of temp gauge wire from the firewall to the sender?
Post by: Rapid Roy on October 15, 2019, 09:19:14 pm

Welcome to the site.