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Dash lights not working properly

Tiny
KENNELDG
  • MEMBER
  • 1998 PLYMOUTH VOYAGER
  • 1.4L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 175,000 MILES
When you turn on the parking lights or the headlights on the dashboard lights come on momentarily then within 3 seconds fade to nothing making driving at night impossible to see the gauges. All the other gauges continue to work and the mileage lights are still bright. Van interior lights also work fine.
I've checked for error codes but none are visible though check 0 is very dim. I've replaced the light/dimmer switch and also the instrument cluster motherboard from the junkyard but problem persists.
What else to check? Must be related to parking lights or headlights even though those work okay.
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Monday, April 12th, 2021 AT 5:31 PM

8 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,874 POSTS
Hi,

I have a feeling this is related to the body control module. If you look at the attached pics, I included the entire wiring schematic for the instrument cluster. In the first pic, I highlighted the panel lamp driver at the BCM. That wire goes to the instrument panel. It is an orange wire.

What I need you to do is check if there is power at the wire when the lamps fail. It would be nice if you could get a test light on it, turn the headlamps on, and then see if the test lamp slowly turns off. If it does, then I would suggest checking the connection at the BCM to make sure it isn't a loose connection or corrosion causing a power loss.

If the test light does the same as the cluster lights and there are no problems at the BCM connector, chances are the BCM is bad.

Here is a link you may find helpful when testing the wiring:

https://www.2carpros.com/articles/how-to-check-wiring

Let me know what you find or if you have other questions.

Take care,

Joe

See pics below.
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Tuesday, April 13th, 2021 AT 8:29 PM
Tiny
KENNELDG
  • MEMBER
  • 34 POSTS
I haven't gotten to the orange wire yet. I assume I have to take off the fuse housing?
I did check one additional item. When I take out the No. 1 or the No. 4 fuse, both of which power the instrument lighting, then when I turn on the headlights the light to the odometer reading and transmission light do not go dim, as they do when the fuses are both in. Not sure if this is related.
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Wednesday, April 14th, 2021 AT 10:34 AM
Tiny
KENNELDG
  • MEMBER
  • 34 POSTS
I tested the orange wire coming out of the light switch. When I turn lights on to either the park or headlights the test light illuminates and then dims (see attachment).
I'm not too good at electronics so struggling with wiring diagrams. Can you tell me which of the 4 plugs on the BCM has the orange wire? Think it may be the top left that is hard for me to get to.
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Wednesday, April 14th, 2021 AT 11:53 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,874 POSTS
Hi,

The schematics are hard for everyone to read. LOL

If you look at pic 1, I attached the plug to the cluster that has pin 6 (the orange wire). The second pic shows the 23 pin connector at the BCM. I highlighted the pin.

I hope this helps. Also, if you disconnect the BCM, first disconnect the battery. Once the battery is disconnected, unplug the BCM and then you can reconnect the battery.

When reconnecting the BCM, do the same thing. Disconnect the battery first and don't reconnect it until you plug the BCM back in.

Take care,

Joe
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Wednesday, April 14th, 2021 AT 7:56 PM
Tiny
KENNELDG
  • MEMBER
  • 34 POSTS
Okay, so the 13 pin connector on the cluster board and the light switch both have an orange wire that turns on then dims to nothing when the parking lights are turned on. I could not find a 23 pin connector on the bcm, because I did not remove the bcm. But the black fuse panel on the front of the bcm has 4 square plugs that have numerous wires coming out. On the lower left plug there is an orange wire that I tested and it exhibits the same characteristics of coming on with the parking lights then fading to nothing within 6-10 seconds.

My guess is that there is a diode or something in the bcm that shorts when it warms up or something. Seems like a major project to replace the BCM, which appears to be the next step. I'm not sure I can find the same bcm part at the Pick n Pull.
Unless I'm missing something, seems like the best option is to get a $1.00 led at the dollar store for night driving. ;-)
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Saturday, April 17th, 2021 AT 2:09 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,874 POSTS
Hi,

I found one more test for you to perform. The two attached pics below are specific to repairing the panel lamp driver circuit. Take a look through them and let me know the results.

Joe
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Saturday, April 17th, 2021 AT 7:29 PM
Tiny
KENNELDG
  • MEMBER
  • 34 POSTS
Okay, so the voltage on the instrument lights, fuse 1, is a steady 11.9 volts. According to the info you sent me that points to the BCM. I got a little light to use in the meantime until I can pick and pull the right BCM. Thanks so much.
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Monday, April 19th, 2021 AT 10:35 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,874 POSTS
Hi,

You are very welcome. Before you replace the BCM, just make sure there isn't a connection issue or corrosion cutting power. Anything is possible.

If you have a chance, let me know how things turn out for you.

Take care,

Joe
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Monday, April 19th, 2021 AT 4:54 PM

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