I just picked up my first Blazer a few days ago and I've run into a few issues with it so far. It's a 1990 K5, 5.7 TBI V8, and I'm having an issue getting the taillights, running lights and gauge lights to work. I did some research and saw that people said to swap out the switch for the headlight knob, and to also check the tailgate area for open wires that might be crossing, broken etc. I swapped out the switch for the headlights today, didn't seem to fix the issue. Also checked the tailgate, everything seemed to be in order along with checking each of the fuses on the panel. They all checked out with a tool my buddy had that checks for the grounds and contacts. I'm brand new to a lot of the GM stuff coming from a Jeep, so I'm at a loss on what to do next. Any help would be greatly appreciated, trying to get this thing road worthy!
CK5
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No taillights, dash lights or running lights
- Thread starter dj31499
- Start date
Don't listen to people that tell you to randomly swap parts.
Is that the only issues you have? Or are you also missing things like the dome lights?
There is a fusible link that handles lighting on the trucks (and other things as I recall, the other link handles ignition, etc) if that is burnt, then you won't get power to certain circuits. You can somewhat test this by checking for 12V to the headlight switch. The headlights (along with brake lights) work regardless of ignition position, because they are hooked up directly to the battery. If you don't have 12V coming into the headlight switch, then you can work back towards the battery. But I'd check whichever is easier. The fusible link for continuity/12V up to the fuse panel, or the headlight switch 12V.
Here's a good resource for you moving forward. Wiring, service, and parts manuals for each year: http://67-72chevytrucks.com/vboard/showpost.php?p=5621043&postcount=1
See if the truck has a trailer hitch or had one,often the harness gets butchered when trailer light plugs are added ,or the wires get all corroded..make sure the grounds to the frame at the rear are intact,and there is a ground wire for the dash cluster that often gets broken ,it is a black wire that bolts to the cowl up near the E-brake mechanism..
rampage
3/4 ton status
Do the brake lights work or is it just when you turn on the running lights that they don’t work?
To answer the first response, I have the headlights, brake lights and dome lights all working. I'm missing the tail lights, gauge lights and running lights. I'll have to get my friend to check out the 12V input to the switch with his multi meter to see if its actually getting power. Also thanks for the reference guide for the wiring, dyeager.
The truck does have a trailer hitch with some harness that looks like it's used to power the lights of a trailer. While I was back there checking everything out, I found a stray red wire hanging down from a harness. I unplugged the harness and hit the brakes, found out that it was for the driver's side tail light (didn't come on with it unplugged, came on when plugged in), but I'm wondering if this is where the issue is coming from. Here are some pictures of what I'm talking about, the light red/pinkish wire comes off the harness, goes to some sort of two socket plug, and continues down into the red wire on the ground (the plug has two sockets but only one is being used by the loose red wire). Sorry in advance for being confusing, not sure what I'm doing.
The truck does have a trailer hitch with some harness that looks like it's used to power the lights of a trailer. While I was back there checking everything out, I found a stray red wire hanging down from a harness. I unplugged the harness and hit the brakes, found out that it was for the driver's side tail light (didn't come on with it unplugged, came on when plugged in), but I'm wondering if this is where the issue is coming from. Here are some pictures of what I'm talking about, the light red/pinkish wire comes off the harness, goes to some sort of two socket plug, and continues down into the red wire on the ground (the plug has two sockets but only one is being used by the loose red wire). Sorry in advance for being confusing, not sure what I'm doing.
The last picture shows up, the rest are red X's.
The taillight wiring harness comes down the DS frame rail and splits out to 2 4-pin weatherpack connectors. One of these goes to each tail light harness. The easy way to install a trailer plug is to buy the little Y-adapter that simply plugs between the two harnesses. Unfortunately, many driveway morons cut up the factory wiring, splice some stuff in and call it success since the trailer lights work (at least at first). The ground for each tailight assembly is a ring terminal bolted on with the taillight. You should see it if you just remove the taillight lens. I was thinking that the brake switch supplies the ground for the brake lights, so having working brake lights doesn't mean it's good.
I just have this sneaking suspicion that I once lost taillights, dash lights and side marker lights and it was a blown fuse under the dash. IIRC there's a weird sneak path where the dome light ends up in series with the under-dash light so they glow dimly sometimes.
The taillight wiring harness comes down the DS frame rail and splits out to 2 4-pin weatherpack connectors. One of these goes to each tail light harness. The easy way to install a trailer plug is to buy the little Y-adapter that simply plugs between the two harnesses. Unfortunately, many driveway morons cut up the factory wiring, splice some stuff in and call it success since the trailer lights work (at least at first). The ground for each tailight assembly is a ring terminal bolted on with the taillight. You should see it if you just remove the taillight lens. I was thinking that the brake switch supplies the ground for the brake lights, so having working brake lights doesn't mean it's good.
I just have this sneaking suspicion that I once lost taillights, dash lights and side marker lights and it was a blown fuse under the dash. IIRC there's a weird sneak path where the dome light ends up in series with the under-dash light so they glow dimly sometimes.
