Dash Light Issue

[SL87Chevy]

Hello All,

Just recently purchased an 87 Silverado.

Here's the situation on the dash lights. The only light that will work on the cluster is the high beam light. I've replaced the head light switch and have replaced the fuse. I tried replacing the bulbs and they still wont turn on. I know its not my bulb installation because they will all work in the high beam light connection.
Before I spend on a new circuit has anyone else had a similar issue? If its the printed circuit why would the high beam light work but not the others? All of my gauges are also working properly. I don't have any other light issues either, all other inside and outside lights work perfectly.

Don't mind buying the circuit but I just to make sure I have the solution.

 

[Charlie]

 

[Obwonkonobe]

I had to go through and map out all those little pins in the bulk connector for the gc. Then pull then out and re pin it. That's because the po put in a different year and style gauge cluster

 

[Derrick]

 

[chengny]

Hello All,

Just recently purchased an 87 Silverado.

Here's the situation on the dash lights. The only light that will work on the cluster is the high beam light. I've replaced the head light switch and have replaced the fuse. I tried replacing the bulbs and they still wont turn on. I know its not my bulb installation because they will all work in the high beam light connection.
Before I spend on a new circuit has anyone else had a similar issue? If its the printed circuit why would the high beam light work but not the others? All of my gauges are also working properly. I don't have any other light issues either, all other inside and outside lights work perfectly.

Don't mind buying the circuit but I just to make sure I have the solution.

Is the lamp in the HVAC control panel illuminating - how about the radio? If they don't work either, that would suggest that the entire instrumentation lighting circuit is not being energized.

The circuit goes like this:

Power from the fuse block (20A T/L CTSY fuse) to the headlight switch on ORN 40. You know that ORN 40 is hot because you have all tail and parking lights working.

The ORN 40 also supplies the line side of the dimmer (rheostat). The load side of the dimmer is connected to the instrumentation lighting. Since you changed the H/L switch, its reasonable to assume that the dimmer is okay.

The variable voltage out of the dimmer is carried back to the fuse block on DK GRN 44. Once inside the fuse block, DK GRN 44 feeds the line side of the 5A INST LPS fuse.

The load side of the INST LPS fuse feeds the GRA 8 circuit which supplies the lamps in the instrument cluster, HVAC panel and radio.

You should take your meter - or test probe - and check for voltage:

1. On the DK GRN at the H/L switch (parking lights on and dimmer turned all the way up). I know you changed the H/L switch but just to be sure.

2. On the DK GRN at the fuse block. Pull INST LPS fuse and put test probe in the one of the clips (I think left clip is power in but IDK for sure, so check both). If you find that there is voltage into the INST LPS fuse, be sure that the fuse is good. Use a meter - don't go by the link in the little window.

3. Last check is somewhere in the GRA 8 circuit. The HVAC panel is probably easiest.

If there is power there (and the lamp is working) then you have a problem with either the printed circuit or the branch that feeds the printed circuit.

You can check your ground connection at the common bus block (down by the parking brake) but since the HI beam light works - and it shares the same ground connection as the other lamps - it wouldn't seem that its a grounding issue.

 

[SL87Chevy]

Is the lamp in the HVAC control panel illuminating - how about the radio? If they don't work either, that would suggest that the entire instrumentation lighting circuit is not being energized.

The circuit goes like this:

Power from the fuse block (20A T/L CTSY fuse) to the headlight switch on ORN 40. You know that ORN 40 is hot because you have all tail and parking lights working.

The ORN 40 also supplies the line side of the dimmer (rheostat). The load side of the dimmer is connected to the instrumentation lighting. Since you changed the H/L switch, its reasonable to assume that the dimmer is okay.

The variable voltage out of the dimmer is carried back to the fuse block on DK GRN 44. Once inside the fuse block, DK GRN 44 feeds the line side of the 5A INST LPS fuse.

The load side of the INST LPS fuse feeds the GRA 8 circuit which supplies the lamps in the instrument cluster, HVAC panel and radio.

You should take your meter - or test probe - and check for voltage:

1. On the DK GRN at the H/L switch (parking lights on and dimmer turned all the way up). I know you changed the H/L switch but just to be sure.

2. On the DK GRN at the fuse block. Pull INST LPS fuse and put test probe in the one of the clips (I think left clip is power in but IDK for sure, so check both). If you find that there is voltage into the INST LPS fuse, be sure that the fuse is good. Use a meter - don't go by the link in the little window.

3. Last check is somewhere in the GRA 8 circuit. The HVAC panel is probably easiest.

If there is power there (and the lamp is working) then you have a problem with either the printed circuit or the branch that feeds the printed circuit.

You can check your ground connection at the common bus block (down by the parking brake) but since the HI beam light works - and it shares the same ground connection as the other lamps - it wouldn't seem that its a grounding issue.

Thank you, I will try this out. It has an after market radio so not sure if that makes a difference on why it works. The A/C panel does not light up.

 

[chengny]

Thank you, I will try this out. It has an after market radio so not sure if that makes a difference on why it works. The A/C panel does not light up.

Yes , it does - make a difference. Most aftermarket head units generally don't use a variable voltage supply for backlighting. If the truck's gray wire is not connected to the receiver's orange wire, its either all or nothing when it comes to backlighting.

Given that you don't know how the stereo is wired, I would not use it as an indication as to whether or not the GRA 8 circuit is energized - just go by the HVAC panel (as long as you know the lamp is good). If in doubt, test the gray wire at the HVAC panel with your meter.

 

[SL87Chevy]

20A T/L CTSY fuse has power. Inst Lps fuse is not getting power. How would i get power to it? all other fuses are getting power. The fuse to INST LPS is new.
Anyone that can tell me where the ground busbar is just to check??

Chengny, thanks so far for the help!! You're awesome