The 1947 - Present Chevrolet & GMC Truck Message Board Network







Register or Log In To remove these advertisements.

Go Back   The 1947 - Present Chevrolet & GMC Truck Message Board Network > 47 - Current classic GM Trucks > The 1988 - 1998 GMT400 Chevy & GMC Pickups Message Board

Web 67-72chevytrucks.com


Reply
 
Thread Tools Display Modes
Old 03-08-2015, 01:55 PM   #1
philster3
Registered User
 
Join Date: Feb 2015
Location: Farmington, MI
Posts: 5
1988 k1500 Tail Light Problems

Hey all. I have a 1988 GMC k1500 in pretty good shape. It's been parked for a couple years while I was out of the country and now it has some kinks that need to be worked out.

Starting a couple days ago, the dir/stop lights are stuck in the on position, even when the truck is off and the key is out. The lights will function as intended with the directional switch is used, but not with the hazard switch. Additionally, when the truck is turned on, the reverse lights will turn on. They will stay on when the truck is shifted from park to drive to reverse and will intermittently turn themselves on and off, regardless of whether the truck is in drive or reverse.

My questions are: Are these two separate issues, or is it possible they are related? Does this sound like a shorted wire, or a faulty switch/relay. Everything with the front headlights and directional lights seem to be working fine.

I'm not great at truck maintenance and electrical systems isn't great so I'd love some help.
philster3 is offline   Reply With Quote
Old 03-08-2015, 11:00 PM   #2
rickpilgrim
Registered User
 
Join Date: Apr 2011
Location: Wausau, WI
Posts: 591
Re: 1988 k1500 Tail Light Problems

The brake light problem is likely the brake switch under the dashboard on the brake pedal.
Reverse lights sound like a switch also.
rickpilgrim is offline   Reply With Quote
Old 03-09-2015, 02:40 PM   #3
Gauder the Goof
Registered User
 
Join Date: Feb 2008
Location: Windsor, Ontario, CANADA
Posts: 15
Re: 1988 k1500 Tail Light Problems

Wonder how the circuit boards on the tails look?
Gauder the Goof is offline   Reply With Quote
Old 03-09-2015, 03:06 PM   #4
philster3
Registered User
 
Join Date: Feb 2015
Location: Farmington, MI
Posts: 5
Re: 1988 k1500 Tail Light Problems

The circuit boards on the tails look fine at first glance. I figure the problem is upstream of them anyway because the brake lights are staying on even with the key out. Something has to be messed up between the battery and the lights themselves because they are getting power. Right?
philster3 is offline   Reply With Quote
Old 03-13-2015, 08:39 AM   #5
68 TT
Still plays with trucks
 
68 TT's Avatar
 
Join Date: Jul 2009
Location: Spokane, WA
Posts: 3,556
Re: 1988 k1500 Tail Light Problems

Quote:
Originally Posted by philster3 View Post
Hey all. I have a 1988 GMC k1500 in pretty good shape. It's been parked for a couple years while I was out of the country and now it has some kinks that need to be worked out.

Starting a couple days ago, the dir/stop lights are stuck in the on position, even when the truck is off and the key is out. The lights will function as intended with the directional switch is used, but not with the hazard switch. Additionally, when the truck is turned on, the reverse lights will turn on. They will stay on when the truck is shifted from park to drive to reverse and will intermittently turn themselves on and off, regardless of whether the truck is in drive or reverse.

My questions are: Are these two separate issues, or is it possible they are related? Does this sound like a shorted wire, or a faulty switch/relay. Everything with the front headlights and directional lights seem to be working fine.

I'm not great at truck maintenance and electrical systems isn't great so I'd love some help.
The turn signals & brake lights share the same wire back to the tail lights so it is possible the turn signal switch is defective and is causing all of your problems or it is a wiring issue at the base of the column where the turn signal and reverse light switch wiring come together.
__________________
miSSed opportunity - ground up creation of an AWD 1994 454 SS that never was http://67-72chevytrucks.com/vboard/s...d.php?t=795577
69 C10 shortbed stepside 400 small block - built like what a super sport truck could have been
69 K20 lwb TBI 350 4L60E NP208 14-bolt Dana-44 w/disc
68 Camaro SS / RS 500hp 439 inch roller cam big block 4L80E
79 Malibu TPI 350 4L60 w/ Z28 steering & sway bars
68 TT is offline   Reply With Quote
Old 03-13-2015, 01:57 PM   #6
philster3
Registered User
 
Join Date: Feb 2015
Location: Farmington, MI
Posts: 5
Re: 1988 k1500 Tail Light Problems

Problem solved!

Well, two problems solved. When at rest, the brake switch interrupts the current flowing to the brake lights. Once the break is pressed, the current is no longer interrupted and the brake lights come on. In my case, the switch was off calibration and so the at rest pedal didn't interrupt the circuit. It's possible to easily readjust the switch so that it works again, but, I already a new brake switch, so I just replaced it.

As for the reverse lights, I pulled the neutral safety switch and found that part of the tab had broken off. As a result, sometimes the switch would catch and move when shifting, and sometimes it wouldn't. Put in a new safety switch and we're good to go!
philster3 is offline   Reply With Quote
Reply

Bookmarks

Tags
1988, electrical, gmc, taillights


Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 10:08 PM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Copyright 1997-2022 67-72chevytrucks.com