Back up lights and brake lights?

[Daves72'GMC]

On my 72 gmc some times the brake lights work and sometimes they don't. How do I adjust the brake light switch? When I put the truck in reverse only one reverse light comes on.Bulb is ok.Any suggestions of what could be the problems? Thank you all. Dave

[mr48chev]

On the backup light. Check to see if you have power to the light with a test light.
You have to have the key on and the truck in reverse. Make sure the park brake is on or the truck is on flat level ground.

You should have power to the contact in the socket.

If you have power there check the ground for that socket.
On these trucks (I drive a 71 daily) the grounds for the lights are quite often the problem.

If there is no power to the socket, backtrack to the connection where that wire ties into the wire to the other light.

On the brake light switch, it needs to be adjusted so that the brake pedal lever just turns the switch off when your foot is off the brake. I think I would be of the notion that the switch may be going bad. The are fairly inexpensive and available at most parts houses.

[Longhorn Man]

it's way more likely to be a turn signal switch going bad though.

[Daves72'GMC]

Help! How do I change the turn signal switch?

[Old Money]

reverse light. i had same problem. the bulb was a little too loose in socket and i tried a couple new ones and checked hot and ground. both were o.k. . i put a little bit of solder on the sides of the bulb to tighten up the gap. it works today and i was told to try this by an electician. i did tis in 03 and it still is the cheapest repair yet. old indian trick. i used to run tin indian 66 tempest custom back in 70 and 71. Pld money

[Daves72'GMC]

How do I change the turn signal switch? Thankyou.

[Daves72'GMC]

Ttt

[Daves72'GMC]

Does anyone know how to change the turn signal switch? Thank you.

[Daves72'GMC]

I have a 72' GMC with the 402BB.What's better to use in our factory A/C system R-12 or freeze 12? Thank you.

[Longhorn Man]

turn signal switch;
rent/buy a steering wheel puller.
Park truck so steering wheel is dead center, straight ahead.
Disconnect battery negitive terminal
pop horn button off
remove large (3/4 maybe?) nut that retains steering wheel
remove steering wheel IAW the instructions included with the puller.
*note, some penitrating oil may be needed if the wheel had never been pulled, as is some light tapping on the large jack bolt on the puller*
Slide horn cancel cam off column shaft
hazzard button
1 if original style red button, break the button off.
2 if later style button with a collar around it, remove phillips screw holding it in place after pushing the button in the on position
Remove 3 large phillips scres holding turn signal lever in place. You'll have to place the lever in left turn mode, and right turn mode to locate all of them.
Remove phillips head scre holding turn signal lever in place
Locate 1/2 moon shaped harness plug under dash coming out of the column... look over where your left shin would be as you are seated in the upright position.
Unplug said 1/2 moon
remove black metal trim piece at the column to dash grommet
slide grommet up to shifter base
pop the metal strip off that covers turn signal harness
*personal preference here*
cut harness plug off. Splice a 2 or 3 foot wire to one of the wires on the switch side of the harness you just cut.
pull switch and harness out of column.
Some wiggling and cussing normally involved
once switch is out, and harness pulled through, cut the wire that you just spliced off the switch. MAKE SURE some is hanging out the top of the colimn, and the bottom.
*again, personal preference*
if replacement switch has large flat harness plug installed, cut it off.
The wire that is hanging out the top and bottom of column... splice it into the replacement switch, and tape up the ends of all wires tightly.
Pull that harness through the column till it is out the bottom
remove the wire that was just spliced... discard wire.
Either reinstall stock replacement flat plug, and obtain a harness adapter or
*personal preference*
splice old 1/2 moon plug in it's place useing high quallity butt connectors.

Assembly is reverse order of disasembly, but no puller required for reassembly.
Be sure to install steering wheel in the wxact same position as it was when removed (Why i always say dead straight is the only way to pull it off)

[Longhorn Man]

I don't think I left anything out... some one please chime in if I did... this is all from memory

[myfirstcarwasa73trk]

i just did mine and with a small screwdrive you can push the pins out one at a time as long as you start with white wire they all fall back in place once you have fed the wires down thur the rubber and then put the pins back in the harness and click the two harnesses back together test all you conections you dont have to splice the wires

[72cheysuper]

One thing you might check before you do all that. I dont know if all of our truck are like this or not. Mine is a 72. The wiring harness for the tail lights disconnects from a plug mounted under the bed in a cross frame. Mine was losing ground causing my brake lights and driverside back-up light to only work some of the time. This happened to me on the way home from Tennessee with the truck. Lucky for me, it was that simple. May be worth a shot!

[Longhorn Man]

the ground has nothing to do with that harness. It only carrys power. The ground is the bed it is all bolted to.

[Daves72'GMC]

Ttt