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Discussion Starter · #1 ·
Hey everyone, I'm long time lurker but first time poster. I've been searching all over for some guidance, but haven't found anything specific to my problem so I figured that I should reach out.

I love my 1995 2.5L YJ and keep it running as my summer fun car. The body is a bit beat up and the undercarriage has a lot of rust, but the mechanicals still function well.

The issue I am posting about:
The speedometer gauge lights have been out for about a year. Now that I have time, I thought I would replace all the dash lights with LED (gauge cluster lights and instrument panel/cluster lights.) Super easy job, right? Well, it seems that I did a good job with all the lights except the speedometer lights still do not work... I can't figure out why only the 2 speedometer lights still do not work, and it is driving me nuts. My skills with electrical are poop, so I'm really having a hard time on this one.

I've tried the following:

  1. Bulb replacement with LEDs (and I even tried known working bulbs.)
  2. Replaced the 2 light sockets (the plastic piece the bulb sits in)
  3. With alcohol I cleaned the contacts, to which the bulb sockets attach, on the gauge cluster. (There was not really any visible corrosion/dirt anyway.)
  4. Inspected the #10 fuse under the dash (5 amp), removed it, re-seated it. (This is for sure the lights for the gauges/dash because I tested the lights without the fuse and none of them worked.)
  5. Inspected the pins and plug for the whole gauge cluster. No visible damage or corrosion (that I can tell...)

I really don't know what else to do, but here are some of my thoughts:

  • Replace the #10 fuse because it is <$1 to replace.
  • The Reostat/Dash Dimmer Switch is finicky. Clean or replace.

Does anyone have any other suggestions? Not having the speedometer visible at night is really starting to get to me, and I'm basically out of ideas.

Thanks in advance!
 

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Discussion Starter · #2 ·
I should add that the actual gauges seem to be working and accurate. The only issue is with the 2 speedometer lights.
 

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With the LED's if I remember correctly, can only be installed 1 way for them to power up. Try installing them 180 degrees of what they are currently(if possible). Diodes allow power to flow in one direction only. I did that swap a few years ago and that was the case for me when I had no light on a gauge. Also your dimmer needs to be turned up all the way and mine do not dim but who cares, right?!


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Do you have power to the speedo light wire in the plug that plugs in the speedo?
There could be a break in the power wire or perhaps the ground wire if there is one.

You can see a schematic if you look for a post by MudMagnetYJ and look in his signature. The last item in his signature is a link titled "Service manuals". Open the link and click on the Factory Service Manual for your year Jeep. In the electrical troubleshooting section you should find a schematic.

Good Luck, L.M.
 

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While LED bulbs are polarity sensitive, you mentioned that you used known good (incandescent) bulbs and they still weren't working. If the rest of the harness is powered up, I would say you've got a break (open or short) in the part of the harness that runs to the speedo lights.

You can check this with a multimeter. You also might want to check the dimmer while you're at it.
 

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Discussion Starter · #6 ·
With the LED's if I remember correctly, can only be installed 1 way for them to power up. Try installing them 180 degrees of what they are currently(if possible). Diodes allow power to flow in one direction only. I did that swap a few years ago and that was the case for me when I had no light on a gauge. Also your dimmer needs to be turned up all the way and mine do not dim but who cares, right?!


Sent from my iPhone using Tapatalk
Good suggestion for rotating the LED's. I double checked, and this is not the issue. :( My dimmer is all or nothing for the LED's as well. It does not have to be all the way up to engage the lights, just above the "off" setting.

I also cleaned all the parts to the dimmer and it functions perfectly now. I again cleaned the conductive surface on the back of the gauges, but still no lights to those 2 lights.
 

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Discussion Starter · #7 ·
Do you have power to the speedo light wire in the plug that plugs in the speedo?
There could be a break in the power wire or perhaps the ground wire if there is one.

You can see a schematic if you look for a post by MudMagnetYJ and look in his signature. The last item in his signature is a link titled "Service manuals". Open the link and click on the Factory Service Manual for your year Jeep. In the electrical troubleshooting section you should find a schematic.

Good Luck, L.M.
While LED bulbs are polarity sensitive, you mentioned that you used known good (incandescent) bulbs and they still weren't working. If the rest of the harness is powered up, I would say you've got a break (open or short) in the part of the harness that runs to the speedo lights.

You can check this with a multimeter. You also might want to check the dimmer while you're at it.
Thank you for the suggestions for checking with a multimeter. This is my next step. I have no clue what I'm doing, but I'm reading and trying to figure it how to use it and how to check the stuff it suggests to check.

This is what I found in the service manual along with the wiring diagram for the connector:
CLUSTER ILLUMINATION LAMPS
(1) Check fuse 10 in fuseblock module. If OK, go to
next step. If not OK, replace fuse.
(2) Turn park lamps on at headlamp switch. Rotate
panel dimmer switch thumb-wheel to HI position,
just before interior lamps detent. Check for battery
voltage at fuse 10 in fuseblock module. Rotate panel
dimmer thumb-wheel towards LO position while observing
test voltmeter. Reading should go from battery
voltage to zero volts. If OK, go to next step. If
not OK, repair open circuit to headlamp switch or refer
to Group 8L - Lamps to diagnose headlamp
switch.
(3) Disconnect battery negative cable. Remove left
or center instrument cluster bezel and main or gauge
package cluster assembly. Unplug cluster connector.
Connect battery negative cable. Turn park lamps on
at headlamp switch. Rotate panel dimmer thumbwheel
to HI position, just before interior lamps detent.
Check for battery voltage at cavity 21 of main
cluster connector, or cavity 7 of gauge package cluster
connector. If OK, go to next step. If not OK, repair
open circuit to fuse as required.
(4) Turn park lamps off. Disconnect battery negative
cable. Remove fuse 10 from fuseblock module.
Probe cavity 21 of main cluster connector, or cavity 7
of gauge package cluster connector. Check for continuity
to a good ground. There should be no continuity.
If OK, go to next step. If not OK, repair short
circuit as required.
(5) Probe cavity 20 of main cluster connector, or
cavities 1 and 13 of gauge package cluster connector.
Check for continuity to ground. There should be continuity.
If not OK, repair open circuit as required.
 

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Discussion Starter · #8 ·
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Thanks again for all the help! I am all good now!

Due to my skill level in trying to track the issue down, I eventually went in a kludge direction... I wired into one of the tachometer LEDs to power both the tachometer LED's and speedometer LED's. Please tell me if I have done something ultra stupid...

My hack-fix:
*I used red 14 gauge electrical wire and some electrical tape.
  1. Cut 2 wires long enough to reach from each gauge and provide some slack (maybe 16 inches?)
  2. Stripped about 1 inch of wire on each side of both wires.
  3. Drilled 2 holes in the bottom of each socket.
  4. One at a time:
    1. Fed the stripped end of the wire up through the bottom of the socket.
    2. Pressed about 1/2 of the stripped wire as flat as I could with needle nose pliers.
    3. Bent the wire over the lead on the socket.
  5. Bent the metal leads of the LED's out about 1/8 inch.
  6. "Jammed the LED's into the socket (This holds the wires in place and allows the LED's to get power.)
  7. Taped up any exposed wiring and extra taped the portions of wire going into the Socket (this way they stay tight while they are mounted.)
  8. Feed wires through the open dash holes for the gauges.
  9. Connect LED's
  10. Connect Power
  11. Test and win!
I tried a few different methods before I figured it out, and one included using hot glue to hold the wires... (Hot glue was a fail.) I'll attach pics when my FTP site stops being broken.

*I did pop the fuse while I was learning how to do this, so I had to replace to 5 amp fuse too. It was under the dash on the driver's side, fuse #10.
 

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