Wiring Issue: Dashboard Sensors All Stopped Working

[JessicaRita]

Hey friends,

Hoping you can help me out with a potential electrical issue on our 2002 Thomas 5.9L Cummins. We were originally having difficulty with the throttle/accelerator sensor, so decided to clean up the wiring and plug ends. We, and when I say we, I mean my partner, meticulously cleaned and replaced everything into their rightful places, but when we decided to go for a test drive this morning we discovered that none of the gauges on the dash are working. They were all working yesterday, so pretty certain it’s an electrical issue.

The fun part is, we don’t have clear direction from the manual or the guide that’s pasted on the door of the electrical panel. Does anyone have an idea of what could be effecting every single dash sensor (gas, temp, oil, speedometer, etc.,) to give us zero readings?

Any insight is greatly appreciated!

[Jolly Roger bus 223]

to help us help you with more concise advice we need to know what you have.
go to the user control panel and fill out your profile or just to get started post it in this thread.
profile is better because it stays with every post.

[JessicaRita]

Okay thanks! It's a flatnose 2002 Thomas Saf-T-Liner w/ 5.9l Cummins and Allison 2000.

i added the info to my profile, hoping that helps.

[kazetsukai]

Originally Posted by JessicaRita

when we decided to go for a test drive this morning we discovered that none of the gauges on the dash are working. They were all working yesterday, so pretty certain it’s an electrical issue.

Can you give a few examples of which gauges were previously working but now not working?


All gauges not working suggests to me the problem is with the dash. Does the dash itself take power from somewhere? Have you checked that connection? Its possible that when messing with that, you inadvertently caused a short, blowing a fuse. Check your fuses for starters.

[JessicaRita]

In regards to examples, it’s every single gauge on the dash: Oil Temperature, Tachometer, Engine Temperature, Volt Meter, (assuming Speedometer, but we haven’t moved). With that said, the ‘wait to start’ lights, warning, and stop all function and cycle through, so there must be some power going to the dash.... will start on checking all the fuses next. Engine does start and idle with no issue.

It seems a bit odd there would be one fuse to ‘rule them all’ but clearly something is up!

[kazetsukai]

Originally Posted by JessicaRita

It seems a bit odd there would be one fuse to ‘rule them all’ but clearly something is up!

Not sure how all of those sensors work, but I did wire in a tank level sensor to watch my grey tanks. The principle behind it is that the gauge takes in 12V, sends it out to the sensor, and compares that to the voltage coming back from the sensor. There may be a fuse dedicated to the "sender" circuit in the panel for similar reasons.


Alternatively, the dash itself might not be getting power but the lights you mention on the dash are powered elsewhere. I'm guessing this is what is going on...



Once you check fuses, you're going to need to show pictures of the dash connections, preferably the underside of the dash itself. And be ready to break out the multimeter...

[Truthseeker4449]

You said you cleaned up connections in the dash? Did you double check that you got everything plugged and bolted back in? Could just be one wire you missed.

[kazetsukai]

Originally Posted by Truthseeker4449

You said you cleaned up connections in the dash? Did you double check that you got everything plugged and bolted back in? Could just be one wire you missed.

I'll second this. Always doubt your own work first when something goes wrong...

[bp1791-unleashed]

Originally Posted by kazetsukai

I'll second this. Always doubt your own work first when something goes wrong...

100% agree with this, and from the description it could be as simple as one overlooked ground wire.

Good luck,
Jim

[Texan]

Sounds like a grounding issue if all gages stop working.

[dozr62]

Check the main dash plug at the firewall and gauge cluster