Reverse / Backup light / Trans position switch

I tried searching this forum, but didn't get any suitable hits. Some threads were for the backup switch on manual transmissions which is entirely different from the switch I have, used on automatic-transmission vehicles located on the lower end of the steering column by the brake pedal.

The "Transmission Position Switch" has failed on my '88 K1500 with 700R4 automatic. This switch operates the backup / reverse lights, but it also "tells" the computer that the transmission is in Park/Neutral or in gear (forward or reverse).

I know the switch is bad, because when I remove the electrical connector for the reverse lights, and jump the wires, the backup lights work fine. Otherwise they're dead. The switch fell apart in my hand when I was removing the two electrical connectors from it. I did not see any screws, bolts, or other fasteners (I think it snaps into place) but I can't tell for sure.

There is no local replacement for the switch, although it's ordered and should be here in a day or two. Therefore, I don't have a switch to look at to see how it's held in place.

I've been all over my "official GM" service manual looking for the removal/replacement/adjustment procedure for this switch. The "Cab Electrical" and "Chassis Electrical" sections mention it, and has a lovely but very small drawing of it installed on the lower part of the steering column, down by the brake pedal. This section tells me to refer to STEERING COLUMN section 3B4 for switch replacement info. The problem is that 3B4 Steering Column section does NOT say anything about the Trans Position/Backup light switch!

HOW DOES THE BACKUP LIGHT SWITCH / TRANS POSITION SWITCH GET REMOVED FROM THE COLUMN? HOW IS IT ADJUSTED?

Thanks, folks.

My '88 manual has a pretty good description and adjust on pages 8B-33 & -34. If yours doesn't, PM me and I'll e-mail you what I have............Steve

MY service manual goes up to 8B25, I have nothing higher than that in the 8B section.

Charming.

Sending PM.

Success! Thanks, in part, to 777stickman sending me a scan of the service manual pages I needed. MUCH APPRECIATED!

The switch snaps into position on the steering column of automatic-transmission cars. (Reverse switch is in the trans on manual transmission vehicles.)

My switch was broken at the tang that moves the electrical contacts that turn the switch on and off, and the switch itself was jammed (which probably caused the broken tang) so that it wouldn't go into the Reverse position. Once I got the switch completely off the vehicle, I polished-up the contacts, added some Syl-Glide lube...but it still wouldn't move properly once it was put back together. That's when I noticed that the tang was broken.

The new switch has an additional contact to show the vehicle is in "Park", but my truck has no electrical connector for that, so it's un-used.


http://hbassociates.us/K1500_Backup_Lights_07.jpg

The OEM number is/was 22509632. The "0" is hard to make out. I thought it was an "8" for awhile.
http://hbassociates.us/K1500_Backup_Lights_01.jpg

http://hbassociates.us/K1500_Backup_Lights_02.jpg

http://hbassociates.us/K1500_Backup_Lights_03.jpg

The switch adjusts by sliding the ridged piece under the locking tab. It's supposed to self-adjust by putting the trans in "Park", but I had to tweak mine by hand otherwise the backup lights came on only with the shift lever pushed towards "Neutral".
http://hbassociates.us/K1500_Backup_Lights_04.jpg

http://hbassociates.us/K1500_Backup_Lights_05.jpg

When I originally pulled the switch off the column, I pulled the switch off of it's snap-together mounting bracket. The new switch comes with a new mounting bracket. Spread the "legs" of the bracket to pop the entire switch assembly into or out of the column locating holes.
http://hbassociates.us/K1500_Backup_Lights_06.jpg

Good job troubleshooting the problem.

Personally, I hate it when my tang breaks.