[Sailing_Faith]

I have been working on this for a couple months.

At first my Odometer PRND would drop off ... no rhyme or reason, just sometimes they would not light up. The trip meter did not work either, so I was bugged as I like to track my mileage very carefully.

Last week it came on for the last time... no amount of coaxing could get it to come on... :think:

Reading produced no mention of this, other then someone who found a chafed wire. I unplugged and cleaned the bulkhead connector and the connectors on the ECM to no avail. :shrug:

Today I took the cluster out, half a dozen red T15 screws later and I was looking at the board.... and found the problem; :banana:

There are three resistors that feed the odometer / PRND display. R401 drops the voltage, and R402 and R403 reduce it more when the headlights are on (to dim the display).

The solder joints on all three were bad, R401 was physically loose on the board.

Reflowed all suspect joints, put it back together and I got this;

:thumbup:

 

[Sailing_Faith]

Something interesting I noticed when the odometer was not lit, the mileage would account as normal (and display once it came back on),... which I expected since I know the odometer reading is stored on the ECM...

What I did not expect is that the trip odometer information only added miles when the indicator was lit. So the trip mileage is calculated and stored in the display module it's self.

 

[Rod's Trucks]

That is a very interesting discovery, and a good job of tracking down an elusive problem.
I wonder why those resistors would have gotten so hot that the solder joints failed.
Are you aware of any past history of overcharging conditions? Too high of a system voltage could cause more heat in those voltage dropping resistors, but it should also have been hard on batteries and lamps.
Rod J

 

[Sailing_Faith]

That is a very interesting discovery, and a good job of tracking down an elusive problem.
I wonder why those resistors would have gotten so hot that the solder joints failed.
Are you aware of any past history of overcharging conditions? Too high of a system voltage could cause more heat in those voltage dropping resistors, but it should also have been hard on batteries and lamps.
Rod J

No, not unless it happened in the first 83,000 miles.... the only thing is that I drive the hell out of it! I have been back and forth, up and down, and even all the way around athis country several times.... that single 100ohm resistor is dropping the voltage by quite a bit to power that indicator.... you looking at the board, it seems like it just stays hot...

If it happens again, I will replace the resistor and leave the leads longer.... there is space that it would be able to occupy. Hopefully that won't be until 540,000 miles. :driving:

 

[Sailing_Faith]

One more picture..

 

[Rod's Trucks]

Yes, should it fail again...your good idea..longer leads; and even bond a small heat sink to it.
Rod

 

[Joe232323]

What if this same issue got caused by wrongly wiring a new radio, would that resistor possibly be the problem, I checked all my fuses and there good

 

[Rod's Trucks]

Joe232323 asked:
"What if this same issue got caused by wrongly wiring a new radio, would that resistor possibly be the problem, I checked all my fuses and there good"
I do not see any way a radio installation could have caused this, unless somebody seriously hacked into a wiring harness looking for a powered lead. There are many other places to find power, without getting deep enough in the wiring to get to this one.
Notice I did not say it is impossible... but really not likely, unless you find well butchered harness.
Rod J
Issaquah

 

[Joe232323]

Joe232323 asked:
"What if this same issue got caused by wrongly wiring a new radio, would that resistor possibly be the problem, I checked all my fuses and there good"
I do not see any way a radio installation could have caused this, unless somebody seriously hacked into a wiring harness looking for a powered lead. There are many other places to find power, without getting deep enough in the wiring to get to this one.
Notice I did not say it is impossible... but really not likely, unless you find well butchered harness.
Rod J
Issaquah

Thanks for the info, it’s the odometer and park drive reverse lights that quit along with the speedometer but it just happened after I couldn’t get a new stereo to power on or anything, also the dimmer switch for the interior lights won’t dim anymore, someone mentioned hooking up the orange illumination wire could have put to much voltage into the whole clusters circuit board? I was just totally lost after checking all the interior and under the hood fuses