blackandgold51
1/2 ton status
I got Headlights that are out on a 1983 Suburban C20 454.
I changed out the fuses but no lights except just the ambers
I changed out the fuses but no lights except just the ambers
CK5
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How To Fix Headlights On A 1983 Suburban C20 454 That Are Out?
- Thread starter blackandgold51
- Start date
Check the headlight fluid?
blackandgold51
1/2 ton status
Nope. Haven't done that before? How I do that?
With the little dipstick on the back side of the headlights.
blackandgold51
1/2 ton status
Wait a minute, is this that prank ?
Well crud, we've been made. Sorry. Just couldn't leave that one alone! There are several things that could be the issue but my first look (after fuse of course) would be the dimmer switch.
blackandgold51
1/2 ton status
Tried that nothing
rampage
3/4 ton status
Isn't there a ground wire that goes to the core support? If so check for corrosion.
beags86
Eastbound and Down
Check to see if the plug is loose, the plug to headlight wears outs and you will need to put a new one on the end. Simple cut and splice. Any parts store carries them.
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Check headlight switch, There also may be a fuseable link in the headlight wiring near the core support.
Headlight switch has a built in thermal circuit breaker ,no fuses or links far as I know anywhere in the light wiring harness--they do that and also run the headlights off the battery so they stay on without the key on,to minimize any chance of losing all your headlights suddenly should there be a short circuit,the lights will blink off and on rapidly if a short happened in that case ,and you'd hear the breaker clicking in the switch..
First thing to check is the bulbs,its rare but sometimes both will fail or one right after another--if they test OK then you'll have to inspect all the wires from the switch (especially the dimmer switch,if its a floor mounted one--I'd jump the wires at the dimmer plug first,and see if they work then,I've had to replace the dimmer switch at least once on just about every GM truck I have owned.)...then check the grounds as noted above at the radiator support and all the wires leading from the fuse box to the headlights,including the plugs that clip on the bulbs..
The headlight switches don't fail very often in my experience unless you had many additional lights running off it or a short circuit burned up the circuit breaker in it..
First thing to check is the bulbs,its rare but sometimes both will fail or one right after another--if they test OK then you'll have to inspect all the wires from the switch (especially the dimmer switch,if its a floor mounted one--I'd jump the wires at the dimmer plug first,and see if they work then,I've had to replace the dimmer switch at least once on just about every GM truck I have owned.)...then check the grounds as noted above at the radiator support and all the wires leading from the fuse box to the headlights,including the plugs that clip on the bulbs..
The headlight switches don't fail very often in my experience unless you had many additional lights running off it or a short circuit burned up the circuit breaker in it..
I am having dash light issues so I was under my truck... but my 82 cab has a silver headlight - relay? it went bad and ive replaced it...
Twice for me it has been the headlight switch gone bad. They get old and fail internally.
I'd like to see this. To my knowledge GM never used something like that. Circuit breaker is integral to the headlight switch, since they are not fused nor run off the ignition switch.
Here it is... and also i have ez wiring 21 harness and lists it in their instructions...
I replaced the harness so long ago i dont remember if my old harness had this...
So its a breaker...
As I recall there are two of those on the panels in normal applications, but from what I can find the headlight switch has a breaker in it....wouldnt make sense to have two. I'll have to review the service manual and wiring diagrams to see what they were doing with those breakers.
I have dis-assembled a headlight switch, and there is no circuit breaker in there at all. Nada.
Odd. I knew there was a reason I was under the impression they used an internal breaker, and the '91 service manual confirms why: "the headlamp circuit starts at the battery positive terminal, goes through a circuit breaker in the light switch and to the switch itself,...." I'd never had one apart, I just knew I'd seen it written somewhere.
It also has a diagram showing the headlight switch with the Red B+ terminal going into "170. Headlamp switch" with "175. Circuit breaker" displayed as being inside the switch, on the B+ input. The wiring diagram for '91 reflects the same, and specifies its a 25A internal breaker.
Not arguing that the manuals are correct, I just wonder where the heck they got that info from if there isn't one in there. Normally when the manuals are mistaken they do something like carry info over from an earlier design, or mix it up with the IFS trucks (like the NP241 diagrams in the R/V manuals showing driver drop), but in this case, I don't think those switches ever really changed?
Only somewhat plausible idea I can think of is that aftermarket switches cheaped out and eliminated it? Or was yours OEM?
It also has a diagram showing the headlight switch with the Red B+ terminal going into "170. Headlamp switch" with "175. Circuit breaker" displayed as being inside the switch, on the B+ input. The wiring diagram for '91 reflects the same, and specifies its a 25A internal breaker.
Not arguing that the manuals are correct, I just wonder where the heck they got that info from if there isn't one in there. Normally when the manuals are mistaken they do something like carry info over from an earlier design, or mix it up with the IFS trucks (like the NP241 diagrams in the R/V manuals showing driver drop), but in this case, I don't think those switches ever really changed?
Only somewhat plausible idea I can think of is that aftermarket switches cheaped out and eliminated it? Or was yours OEM?
I know the older square bodies and '67-72 vintage GM cars and trucks have a thermal overload circuit breaker made in the original headlight switches...it looks like a set of points on a bi-metallic strip..
There has to be some kind of protection should a headlamp wire get grounded out,or a lot more vehicles would be burning up..
...adding many aftermarket lights to the circuit will make the thermal overload contacts make & break and the lights flash on and off ..
You'll hear the contacts clicking when they heat up and cool off..
I sold many new switches to the local police department mechanics and other town vehicles like DPW trucks due to this,and many still had it happen,until they wired in relays to take the load off the headlight switch..so I doubt aftermarket switches "deleted" the thermal overload circuit..
I don't recall ever seeing any circuit breaker in the fuse box for headlamps,or fuses, on any of my older trucks,they must have started doing that after the cab style changed in '88 maybe ?..
There has to be some kind of protection should a headlamp wire get grounded out,or a lot more vehicles would be burning up..
...adding many aftermarket lights to the circuit will make the thermal overload contacts make & break and the lights flash on and off ..
You'll hear the contacts clicking when they heat up and cool off..
I sold many new switches to the local police department mechanics and other town vehicles like DPW trucks due to this,and many still had it happen,until they wired in relays to take the load off the headlight switch..so I doubt aftermarket switches "deleted" the thermal overload circuit..
I don't recall ever seeing any circuit breaker in the fuse box for headlamps,or fuses, on any of my older trucks,they must have started doing that after the cab style changed in '88 maybe ?..
My 84 has that breaker as well. Fortunately it's one part of the truck that seems to be cooperate with me for now
