Cluster illumination trouble shooting help

[jballard81]

94 ranger, dash wasn't lighting up on the tach side. so pulled it apart and replaced the 194 bulbs.
I initially replaced them with LEDs, which was a bad idea. but plugged it in, and turned the lights on and all of them flashed on then turned back off. So it was at least working at that point.

realized the error in my ways and replaced the LEDs with standard long life Sylvania bulbs. plugged it in and turned on the lights and now the cluster lights don't work at all.
key on will light the other bulbs at the bottom of the cluster.

pulled the cluster back out and tested the lights on the bench (with a 9v battery) and they worked. i traced the flexible printed circuit and i see continuity from one plug to the other.
i checked the 10a fuse and it tested fine.
i cleaned up the printed circuit contacts where they are plugged in and the connectors themselves and still nothing.

any advice on further trouble shooting? It 'feels' like a connector issue, but it's weird that the other dash lights still work in that instance.

*Edit* just realized i put this in the wrong section. my apologies!

 

[RobbieD]

The other dash lights share the same ground as the rheostated illimination lights, so it sounds like the ground side is OK and you're getting an open circuit on the power side with the cluster in place.

The way the cluster jams into its mounting location may be twisting the connector causing a poor electrical contact; do the lights work with cluster loose, but then they go wonkey as you push the cluster into place?

The terminal itself may bent down, limiting how hard it contacts the printed circuit contacts. Many times I've used a small seal pick to hook under the terminal contact finger, and give them a little "bend" upward to make better contact.

It's also pretty easy to pry the locking wedge out on the connector, and unlock and slide out a terminal for inspection. It's rare, but the point where the copper wire strands are crimped into the terminal can fail.

Final thought, it can be tough to find, but the copper ribbon inside the flexible plastic can fracture, causing an intermittant open condition. Usually takes a strong magnifier and good light to see a fracture, and the real suspect area is where the printed circuit bends to go into the connector contact well.

I think that you got yourself an EVTM for the truck; if not let me know if you need schematics posted.

I'm curious what you find, and good luck!

 

[jballard81]

The other dash lights share the same ground as the rheostated illimination lights, so it sounds like the ground side is OK and you're getting an open circuit on the power side with the cluster in place.

The way the cluster jams into its mounting location may be twisting the connector causing a poor electrical contact; do the lights work with cluster loose, but then they go wonkey as you push the cluster into place?

The terminal itself may bent down, limiting how hard it contacts the printed circuit contacts. Many times I've used a small seal pick to hook under the terminal contact finger, and give them a little "bend" upward to make better contact.

It's also pretty easy to pry the locking wedge out on the connector, and unlock and slide out a terminal for inspection. It's rare, but the point where the copper wire strands are crimped into the terminal can fail.

Final thought, it can be tough to find, but the copper ribbon inside the flexible plastic can fracture, causing an intermittant open condition. Usually takes a strong magnifier and good light to see a fracture, and the real suspect area is where the printed circuit bends to go into the connector contact well.

I think that you got yourself an EVTM for the truck; if not let me know if you need schematics posted.

I'm curious what you find, and good luck!

-doesn't matter if the cluster was pulled out or pushed back into place, no lights either way .

-i thought for sure it was one of the terminals as well. so i carefully pried all of them up a little. no lights

-inspection of the connectors at the terminals seems ok, no obvious breaks in the wiring leading up to them. According to the EVTM, pin 3 on the gray connector (LB/R) should get 12V when the multi-switch is put into park or headlights. I get nothing on pin 3. I pulled the multi-switch and go through the test procedure and it is doing what it is supposed to. But thought maybe i could see if i get 12V between 484 and 19 on the multi-switch when in park or headlight position. i do not.

i did the above testing with the cluster out. i just noticed that i don't have any parking lamps. does the cluster need to be plugged in for the parking lamps to work?

 

[RobbieD]

No, cluster unplugged won't kill the parks. Check the fuses.

Lt Blu/Red is rheostated (i.e.- a dimmer circuit); is the headlight switch knob turned counterclockwise, up to the detent which will turn the dome light?

 

[jballard81]

No, cluster unplugged won't kill the parks. Check the fuses.

Lt Blu/Red is rheostated (i.e.- a dimmer circuit); is the headlight switch knob turned counterclockwise, up to the detent which will turn the dome light?

I measured ohms across the dimmer circuit and it performed as expected.

I tested the cluster with the knob fully clockwise as well as turning it all the way back down to the dome light detent. no difference

i popped the fuse for the park lights somehow. i replaced that 15A and park lights are working again. would that stop the cluster from lighting up? i guess i can plug it in and test it out...

**Update** The answer to my question above is yes, if the 15a fuse for the park lights is blown, your cluster lights will NOT work. Mine work now

i could have sworn i checked all of those fuses 3x but obviously i had not. thanks for the help @RobbieD I really appreciate it!!!

 

[RobbieD]

i popped the fuse for the park lights somehow. i replaced that 15A and park lights are working again. would that stop the cluster from lighting up?

Yes.

 

[RobbieD]

When the cluster is out, test for voltage on Lt Blu/Red at pin #3 on C250, with lights on and dimmer up. That should tell you whether it's the cluster side, or, on the light switch and wiring side.

 

[jballard81]

It was the fuse for the park lights. Just finished getting everything back together. The newly acquired key in switch sensor works!

Both door jamb switches work and the courtesy light works as it should. I think that's the end of my lighting gremlins (hopefully!)

Now onto dealing with the rabs and e-brake plunger sensor thing. Probably just going to pull the rabs fuse and call it good. I'm gathering parts so that I can do a full brake job and all the bearings.

Also need to pull out the code-alarm box and see if I can at least change the dip switches to stop the doors from locking during ignition.