I've had a shifter-related short on my instrument panel and stereo lights for close to two years now. Initially, the lights would come on when I started the truck, but then "blink off and then on" as I shifted from Park to any other gear. It progressed to where the lights would just not come on until I shifted out of Park. In the last two weeks, though, it got so bad I almost could not get the instrument lights to come on even after shifting into D.

I compiled all the info I could find on replacing the shifter tube and did the replacement on Saturday (Dorman shifter tube kit from O-Reilly's). While everything was opened up, I carefully inspected all of the wiring harnesses and connectors carefully, but could not find any evidence of a shorted wire anywhere. I had to proceed, and installed the new shift tube hoping it might have just been a loose connection before the R&R.

Results...
Shifter Movement: Separate Thread HERE >>> https://www.ford-trucks.com/forums/1...l#post16787245

Lighting: No success! The dash lights simply won't come on any longer in any shift position. I DID, however, discover that this is ONLY true when I have my headlight switch in "Auto". When I move it into either the "Parking" or "ON" positions, the dash lights work perfectly. Since I have always kept my headlight switch in Auto, I do not know if it was the same before I did the work on Saturday, but I have no reason to suspect that it wasn't. I am suspecting a single wire between the switch and the shifter, but am just not sure.

So here is my question:

1. Is it possible that my lighting issue is more related to the headlight switch? If so, then why did jiggling the shifter in the past sometimes cause the lights to come on?

2. What else am I missing here?


As always, thanks ahead of time for any and all input.

 

Bumping up, hoping for some input.

 

Is it only the dash lights or are running/other lights affected

 

Do you have a scan tool capable of looking at the PID's?

 

The dash lights should get power from the LB/RD wire fed from the Main Light Switch.
The brown wire (running lights) needs to have power to feed the LB/RD via a circuit in the main head light switch.
The autolamp selection on the switch sends power (via the DB/WHT wire) to the vehicle security module. In that module are headlamp and parking lamp relays. So, if the dash lights are acting up, the running lights may be as well. If it is affecting the headlights as well, that will be good to know.

 

Sorry for the delayed response. Once I got home last night, I got distracted with other stuff and am just now checking back in again. Thanks for those details, blkjck. Now to answer your questions.

1. The exterior lights (headlights and parking lights) come on automatically as they should when the main head light switch is in Auto and the key is on... ONLY the dash lights and stereo lights are not coming on. That said, the stereo itself does come on even though it's display lights do not.

2. In either Park or ON positions for the headlight switch, ALL lights come on as they should.

3. The dimmer switch functions just as it should, also.

4. Given the way this has transpired, I am suspecting a broken wire but cannot find it (yet). Like I mentioned above, it all started with the dash and stereo lights simply blinking off and then on again as I shifted from Park to some other gear position. Then it got to where as long as the gear selector was in Park, the dash and stereo lights would not come on at all until I shifted the lever out of Park. Then, it got to where the lights just stayed off (dash and stereo) unless I wiggled the shifter after getting into Drive.

5. I have AE, so I assume I could get to the PID's, but would need some guidance as to how to get there (navigating through the AE menus) because it's been quite some time since I last tried to dig deeper into the caverns within AE.


I did get some wiring diagrams printed out last night, but have not yet got them all organized or had enough time to start tracing out the connections and connectors to identify the potential individual wires which may be the problem. Perhaps I can get to that tonight.

 

With this information, I would think there is an issue with the parking light control in the vehicle security module or the wire that feeds back to the headlight switch from there.

It looks like the BN 18g wire at pin 2 on the 14pin connector at the VSM gets spliced in to the other running light wires behind the dash panel in the center.

My guess would be that is right near the steering column

 

That makes good sense to me and is along the lines of thought which have been running through my mind. I think it is very telling how wiggling and moving the gear shifter had a definite impact on whatever short there is. For the life of me, though, I just could not see any evidence of a short in the loomed and taped wiring harnesses and connectors right on top of the column.

I did not, however, inspect the looser runs of wiring behind the shifter tube where the backside bracket moves the gear shift cable. I suspect I will find something awry back there when I can get some time to poke my head back up in that hole again (gotta wait for some of the seasonal rains to give me a dry window in which to work (the truck just does not fit in the garage).

 

That, I understand... My friends '99 can only nose in.
You may not see any damage. It could be broken at the splice or somewhere along the wire. You will need to take some voltage and resistance readings.

 

That's the reality about which I've been hoping against hope.

That said, though, since the short was initially occurring only in conjunction with the shift lever movement, I'm going to be looking for stress points along the path for anything which moves when the shifter linkage moves. I know it's possible, but I highly doubt it's within a loom or wire insulation in an area which only may have slight bends to it. I almost has to be at a contact point where wires get nudged, rubbed, pushed, pulled, etc. as the gear shift mechanisms move when changing to/from P/R/N/D.