Temp Gauge Wiring...Kinda lost!

[Paradise Ridge]

Howdy All,

Temp gauge on a '82 K30 W/ 454.

I've replaced the circut board on the back of the instrument cluster and also the Temp sending unit on the engine.

Turned on the ignition and checked the three gauge connectors on the cluster with a 12V tester and nuthin' on any of them.

Which one should be hot? I inspected the green lead from the temp sensor and everything seems fine, I'm just not getting power. Is it OK to prod the circut board with the tester? Should one of the leads supply 12V to the 3 clips that the gauge clips into?

I've searched the archives, but couldn't find anything on our style of truck.

Ideas?...Theories?... I don't want to blow anything in 90 degree heat while I'm dragging by bobcat around the neighborhood!

Scott

[apstguy]

What do you mean by 12 volt tester? Try a multimeter - If you mean a 12v lamp, it proabably wouldn't light because the coolant sensor runs on resistance or variable voltage (probably resistance - don't remember which) either wouldn
't light the lamp. Have you replaced the gauge? Make sure you got the CORRECT circuit board for your truck as they changed alot from year to year. The ground lead to the sensor should be easy to find as it is tied into alot of the other gauges.

[NeCrOmAnCeR]

Yes, the guage should have a 12 volt source from the ignition switch. It then grounds itself through the sending unit on the engine. Since you have replaced the circuit card (for lack of a better word), double check to make sure it is the correct application and then check the connection points and clean them with a pencil eraser.

[Paradise Ridge]

Thanks for the help guys!

Yep it's the right circut board, I got it from the local Chev dealer. My inner dash panel has three clips, one at 9:00, 12:00 and 3:00 when you are looking at it installed in the dash. My temp gauge has 4 posts, one at top, bottom, left and right. The top (12:00) post and the bottom (6:00) are jumpered.

I've tried another gauge with the same posts from another truck and the gauge still reads zero, and both gauges work in the other truck.

I purchased a wiring diagram from Year One along with my last order, but it doesn't help.

Does anybody know which socket (9,12 or 3) should be hot? I'd be glad to run a temporary jumper from an ignition hot until I can track it down further.

Thanks!

Scott

[Paradise Ridge]

P.S.
When I replaced the circut board, I cleaned EVERY connection with emery cloth. All the lights work, along with the turn signals, 4 wheel indicator, and the other gauges. It's just this one that is throwing me.

Good Idea about the pencil eraser, though!

Scott

[Grim Reaper]

Anything else not working?
Sounds like no power to the board. I though all the gages shared main positive but maybe I'm wrong. Iwould think if now power you would also have no gas gage and possibly no volt meter.
See if you have a fuse spot marked gages AND clock. Check those fuses. The mechanical cloks use to be a seperate fuse. They were so prone to fail the fuesed seperate so when the clock fried you didn't loose the gages. Not sure how far that carried. My 75 is that way but I honestly don't remember if my 79 I sold was and I'd have to look at my 88 when I get home. It might be the Clock also fees the temp gage.

Did you meter between the conection at the sender and the cluster?

Check the bulkhead connector. There is a single bolt in the center and removing that will let the plugs for engine and body harness be removed. We were chasing a problem on a buddies Vandura and ended uo finding one of thos conection came unseated and pushed part way out hte back of the block. Maybe the same problem if you don't have continuity between the sender and cluster.

[Grim Reaper]

Ohh yeah if you ground the end at the sender it should peg the gage.