Instrument cluster woes

GerhardUngerer · Mar 15, 2021

I am in the process of replacing the dashboard on my FJ80 and decided to upgrade the instrument cluster bulbs to LED. After I tested it out, the center PRNDL worked for a second, then stopped working. I put the bulbs back in and it just gives a dim glow. Also, the bottom row of indicators doesn't seem to light up when I switch the key on. Going back to bulbs didnt do any good. Did I let the smoke out? Advice?

There used to be a white indicator light that came on right bottom, above the diff lock lights. No more. ???

Is there a way to test the instrument cluster on the bench?

GerhardUngerer · Mar 15, 2021

Is there a way to bench-test the instrument cluster?

DivByZero · Mar 15, 2021

GerhardUngerer said:
Is there a way to bench-test the instrument cluster?

I'd check your fuses. Did the gauge fuse pop? I'd take a good look at the connectors to the cluster too. Are you sure you seated them back in snugly? Did you try unplugging them and seating them again, and giving them a bit of a wiggle?

South Texas 97 · Mar 16, 2021

I suspect these could be two separate issues, as the PRND2L lights are not really part of the cluster, they are in a separate module inside the cluster, but you know that already. I would certainly check the fuses, and if you have a circuit diagram of the module, you should certainly be able to bench test it, at least with 12 volts. Check all grounds as well, as not having a voltage return will cause them to not light up.

I have a 97 electrical manual if any of those diagrams would be useful to you?

flintknapper · Mar 16, 2021

South Texas 97 said:
I suspect these could be two separate issues, as the PRND2L lights are not really part of the cluster, they are in a separate module inside the cluster, but you know that already. I would certainly check the fuses, and if you have a circuit diagram of the module, you should certainly be able to bench test it, at least with 12 volts. Check all grounds as well, as not having a voltage return will cause them to not light up.

I have a 97 electrical manual if any of those diagrams would be useful to you?

He can even check most LED's with a simple 9 volt battery if that's more convenient.....for bench testing.

GerhardUngerer · Mar 16, 2021

DivByZero said:
I'd check your fuses. Did the gauge fuse pop? I'd take a good look at the connectors to the cluster too. Are you sure you seated them back in snugly? Did you try unplugging them and seating them again, and giving them a bit of a wiggle?

Yep, I checked the gauge fuse and it is ok. Plus, it would affect all the gauges, right? Not just a few? I pulled the connectors out and reseated them several times. No luck.

GerhardUngerer · Mar 16, 2021

flintknapper said:
He can even check most LED's with a simple 9 volt battery if that's more convenient.....for bench testing.

I tested them with a multi-meter and they all tested out fine.

GerhardUngerer · Mar 16, 2021

South Texas 97 said:
I suspect these could be two separate issues, as the PRND2L lights are not really part of the cluster, they are in a separate module inside the cluster, but you know that already. I would certainly check the fuses, and if you have a circuit diagram of the module, you should certainly be able to bench test it, at least with 12 volts. Check all grounds as well, as not having a voltage return will cause them to not light up.

I have a 97 electrical manual if any of those diagrams would be useful to you?

How do I check the PRND2L lights? I completely backed out all the LEDs and installed the bulbs again. Still doesn't work.

Also, none of the warning lights (oil, etc) work. Could this be ECU related?

Pz10420 · Mar 16, 2021

So you reinstalled the incandescent bulbs and it still doesnt work? If so, then I would pull the whole cluster out and start bench testing it and like others have said check for bad grounds.

Pz10420 · Mar 16, 2021

Also, you know that a lot of LEDs are polarity sensitive and if they dont work one way flip them 180 and retest.

flintknapper · Mar 16, 2021

Pz10420 said:
Also, you know that a lot of LEDs are polarity sensitive and if they dont work one way flip them 180 and retest.

^^^^

Yep. Some are some are not.

I always 'test' any LED that I am going to install with a 9volt battery and some leads. It's not enough to check them for continuity with a multi-meter. LED's can burn out the second you apply power, flicker, etc.... You just don't know until you put power to them. Good quality LED's will work and last a long time though.