Funky Temp Gauge

[CornRickey]

I replaced my tach speed, temp and volt gauge recently. All replaced by Farai on warranty. The temp gauge was replaced for a original.al model. The PO replaced it with a different model but kept the original, I sent it in with the others. The other temp gauge worked fine. Took the boat out today for the first time since the replacement. The temp gauge flicker at idle and goes directly to 160ish at speed. When I go back to idle it drops back down to about 100 and flicker. This is a electrical issue, the engine temp isn't changing like the gauge shows. I'm very familiar with ground issue and have checked the leads going to the gauge. It's all looking good. I'm assuming this is a contact issue under the dash and will tear into it more. I'm asking to see if anyone else has experienced this symptom to see if I'm missing anything. Thanks.

[Salty87]

kinda sounds like it's hooked to the tach wire instead of the heat sender.

[CornRickey]

Nope. But I'm wondering if there is a cross feeding from another lead. The gauge was theast to be replaced. Removed the leads from the old one and installed them on the new.

[CornRickey]

Alright I've been dealing with this for a while and still haven't figured it out. I removed the sending g unit and it looked fine. The gauge will start jumping around sometimes drop to 100 and stay there sometimes go to 165ish and bounce. Sometimes I can reach under the dash and move around the wiring harness and it will cause it to bounce. I've followed the wires and all check out. The brown signal wire goes to a harness plug. I cleaned it.

Today I took another gauge with me and hooked it up to the posts on the gauge in the dash by alligator clip leads. The gauge didn't jump as much but stayed at about. 110. I'm thinking the gauge in question is faulty and reason for the lower temp reading is due to two gauges hooked up to the same signal lead. A interesting thing is when I did hook both up the gauge in the dash went dead.

What's your thoughts?

[DAFF]

I wonder if a scanner would read the temps correctly. Seems to me the guage could of been droped or has continiuty issues.

[OUI]

You temp gauge is nothing more than a volt meter -- your temp sensor is nothing more than a variable resistor. Pull the wire off the sensor and touch it to the block, it should peg the needle. It it doesn't than you have a problem with the wire going to the gauge or the gauge is shot. It it doesn't peg, then check the wiring with a volt meter. Pull the wires off the gauge and connect it to the volt meter the voltage should rise and fall with the engine temp going up and down.

[CornRickey]

Well I think I figured it out. After digging around and not getting anywhere I hooked up the lead on the gauge to my meter and ran another lead to the connector for the sender. I was getting 120 ohms. So that wasn't right and I started wiggling harnessed from the sender forward. When I got to the pin connector below the 40 amp breaker my meter buzzed . Once I figured out how to take it apart I found one of the female sockets dirty and the rubber swelled up around it from getting hot. Cleaned everything up and it checks out with my meter. I pretty confident this was the issue but will have to wait till Sunday to get it out on the water.

[CornRickey]

Got it on the water yesterday (for 9 hours I may add) and it held rock solid on 175. Problem solved.