Odd electrical issue with gauges.....

[hammersley]

OK.....I have an A pillar with 3 gauges and a 4th Fuel Pressure on steering column. A few weeks back my gauges stopped working unless I had my Lights Turned on...which I always have. So I installed a new Headlight Switch ...from Oreillys.
Not only did it not solve the problem....it made it worse....with the new switch....NONE of the 4 additional gauges worked! So i put the old one back in....worked as before....meaning everything ONLY worked when the headlights were on!

Also intermitently the Fuel Pressure Gauge and the EGT were giving way false readings.....like at idle the EGT's were 1200....the FP....20+. Normally the FP is 15 and the EGT's at idle (with no hard work) will be at 400 ish.

NOW today...MY Oil Pressure gauge--on the factory top right gauge....goes from 50 to 0....and then back again...No reason....not affected by headlight switch...however I did restart and temporarily It also rings a bell and the dash says Check Gauges....OK....HELP.....what to FIX?????

 

[PBJ2500CTD]

hammersley,

The oil pressure symptom is typical of a faulty oil pressure sensor. As far as the other gauges, I would check the gauge wiring, especially the grounds.

 

[hammersley]

Thanks so much .. will check....

 

[Joe Mc]

I had whacky situations with my trans temp and fuel psi gages, EGT and Boost (non-electrical) no problems ever. I ended up providing trans temp and fuel with their own separate grounds = problem fixed. Never anything as odd as what you are having and thank god no problems with stock gages. I’d check all grounds for sure and make certain the power source for your aftermarket gages is coming from a “switched by ignition” fuse. Sounds like there might be a cross up in wiring for gage lights to the power for the gages. If you have the headlights on and turn the dimmer up and down do the gage readings change?

 

[BarryG]

On my 01 my oil pressure gauge would go wonky like you are saying. It turned out to be the sender. I think this is a separate issue from your aftermarket gauges.

Interesting that your gauges only work with the lights on. By chance do you have your gauge lights tied into the truck light circuit, sounds like it otherwise why change the mf switch? If so the lighting on an 01 is negative switched if I recall. And as such your gauges may not be getting a good ground unless the lights are on. My aftermarket gauges were not tied into the truck light circuit so I am unsure how they are hooked up that way I just seem to recall reading that if you tied them in to the oem circuit it would provide gauge lighting and the dimming functionality as well. Do you perhaps have a common ground for all the gauges, if so and even if not, I would check that ground from end to end.

I may also be remembering it all wrong as it has been a while and the above is just a bunch of hooey but certainly worth checking the gauge grounds either way.