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Sybf · 10-28-2021, 07:57 AM

Our engine temp gauge increased to "hot" and others on the dash flickered dramatically when the headlight/dash lights are turned on. We replaced the switch last year because the overhead driver's map light would not go off and driving after dark was impossible. We reacted to the gauges by adding coolant, new thermostat until we realized when we turn off the headlights, the gauges returned to normal. So we are not sure if it is a bad switch or if turning on those exterior lights puts a load on the alternator/voltage regulator. Has anyone experienced this problem?

Davdeb1 · 10-28-2021, 08:06 AM

If this happened after replacing that switch, it has to be the source. Also, the overhead light thing could be telling. If you replaced the light switch yourself, you know just how many wires are behind that dash. If someone other than you replaced the switch, you may have the wrong switch.

Skip426 · 10-28-2021, 08:06 AM

I would suspect that the dash gauge lighting and the actual gauges are fighting for ground . Where your instrument panel is grounded probably has a bad connection .

Colin Jarvis · 10-28-2021, 08:09 AM

You appear to have aground problem

This happened on my rig a few years ago

I corrected the problem by running a ground wire from metal piece on the

switch to metal framing under dash ensuring that frame coating was scrapped

down to bare metal for a good ground

Ljwt330 · 10-28-2021, 08:57 AM

I will just add that I agree that the problem seems to be a grounding issue.

Your symptoms are consistent with the lighting receiving a ground or partial ground through the gauges.

wolfe10 · 10-28-2021, 09:01 AM

Good answers. Inadequate ground is the likely suspect and an easy one to fix. If tracing the OE ground is difficult, merely add a new one.

ccdriver99 · 10-28-2021, 09:29 AM

Agree with all of the “bad ground” replies. I would also suggest that you obtain a BlueFire app that will show the gauges in digital format. Inexpensive and gives you peace of mind even if you only use it as a backup to your analog gauges.

153stars · 10-28-2021, 11:27 AM

Look above genny for ground bus bar clean and tighten these . This just helped other poster recent thread. There were other bus bar under dash that he did get into later as well for lingering issue.
I clean and tighter and grounds I stumble across in my repairs and tinkering around. There were tons of small frame grounds in my Generac 75D when I had it tore apart.