Temperature Gauge / Sending Unit

[69RRJohn]

Hello all, I have an electrical problem and hope someone can steer me in the right direction. My temperature needle pegs while driving and my tach/DC gauges are also erratic while the needle is pegged. In regards to the temperature gauge, I've changed the thermostat, there are no visible signs the old thermostat was bad. Also, there's no indication of engine overheating (smoke from the engine....etc.) and my dual fan Griffin fans (with a relay for each) come on as advertised. Also weird is that when I'm stopped and shift to neutral at a light or wherever, my temperature needle swings a little to be the left. Can this be inter-related?

I truly believe this to be an electrical issue somewhere between my gauges and the sending unit/shifter...etc. Does anyone have any experience with this who can provide some help/direction? My Bird is a 1969 383 3-Speed Automatic with the shifter in the center console.

 

[Russ69Runner]

Their is a voltage limiter on the mother board or plugs to the board. Classic industries sell them. I would lean towards that being your problem. Here a lot of guy's have to replace it. Their may be more guy's here that can tell you how to install it. Had my instrument cluster redone so it was put on when they did my board.

 

[halifaxhops]

The VL does gas and temp so if it is only the temp not a VL. Easy to troubeshoot take the wire off the temp sending unit and ground it it should peg, off it should be low. If not it is between the wiring and the gauge, Sending unit operates between 10 and 73 ohms so at temp it should be between there. Hope it helps.

 

[69RRJohn]

Thanks a bunch. Will check it out.

 

[69RRJohn]

Their is a voltage limiter on the mother board or plugs to the board. Classic industries sell them. I would lean towards that being your problem. Here a lot of guy's have to replace it. Their may be more guy's here that can tell you how to install it. Had my instrument cluster redone so it was put on when they did my board.

Russ, played with it yesterday and believe I have a bad VR. Ordered from Rock Auto but I’m looking at all options from the responses. Thanks a lot.

 

[mac]

Russ, played with it yesterday and believe I have a bad VR. Ordered from Rock Auto but I’m looking at all options from the responses. Thanks a lot.

the voltage limiter and the voltage regulator are two separate items.

 

[Ranger]

This may or may not be relevant, but for what it's worth, here goes. My '69 Road Runner (383) had a bouncing tach. All other gauges where normal. Long story short, it turned out to be failing insulators in the amp gauge. I bypassed it and the problem went away.

 

[Russ69Runner]

Hope you can resolve the issue. At least these cars are not all computer run and we can work on them. Hope the problem's get worked out and you can get back to enjoying that runner.