No dash or dome lights

[flyboy1100]

Things checked so far.

fuse and power to fuse. Fuse was blown so I replaced it, no joy. checked power with a test light and that is the only fuse in the entire box that doesn't have power.

where do I go from here?

 

[BADAZ chevy guy]

Headlight switch? See if you're getting power out of it.

 

[flyboy1100]

thanks.

is that how the fuse gets it's power, from the switch? the electrical diagrams in a Chilton book are horrible.

 

[HotRodPC]

I too would suggest headlight switch. IIRC, The dome lights and dash lights are on different circuits but both do run through the hl switch. If it was a fuse, your tail lights also wouldn't be working when the dash lights aren't working.

 

[BADAZ chevy guy]

thanks.

is that how the fuse gets it's power, from the switch? the electrical diagrams in a Chilton book are horrible.

No. Power starts at the battery, then goes to the fuses, then goes to the dome lights. The ground side of the dome lights go to the headlight switch and to the door switches.
There's two sides to the headlight switch as HotRodPC said. One side grounds the dome lights when turned to the far Left. The other side sends power to the head, tail and dash lights.

 

[BADAZ chevy guy]

You didn't mention what year your truck was, but you can find all the wiring diagrams for squares here. >>> http://forum.73-87chevytrucks.com/smforum/index.php?topic=11766.0

 

[flyboy1100]

You didn't mention what year your truck was, but you can find all the wiring diagrams for squares here. >>> http://forum.73-87chevytrucks.com/smforum/index.php?topic=11766.0

No I Didn't, 1986. It says under my user name. Maybe I will make a signature.

Thanks for that link, I will give it a look.

 

[flyboy1100]

No. Power starts at the battery, then goes to the fuses, then goes to the dome lights. The ground side of the dome lights go to the headlight switch and to the door switches.
There's two sides to the headlight switch as HotRodPC said. One side grounds the dome lights when turned to the far Left. The other side sends power to the head, tail and dash lights.

Hmm, I'm still confused as to why the dash light fuse is the only one in the entire fuse box w/o power on either side of the fuse.

Tomorrow I hope to get time to pull the fuse box and head light switch to test them out.

 

[BADAZ chevy guy]

If the rheostat wire (Inside the headlight switch) has broken and shorted against the case it could have blown the fuse.

I hope you don't find this insulting, that isn't my intent. I just know there's a lot of guys who get hung up on trying to remove the headlight switch. Here's a 'How to' video on pulling the switch out. >>> https://www.youtube.com/watch?v=wxZIjY8EbZ8

 

[flyboy1100]

If the rheostat wire (Inside the headlight switch) has broken and shorted against the case it could have blown the fuse.

I hope you don't find this insulting, that isn't my intent. I just know there's a lot of guys who get hung up on trying to remove the headlight switch. Here's a 'How to' video on pulling the switch out. >>> https://www.youtube.com/watch?v=wxZIjY8EbZ8

Not at all, I would have probably gone looking for one. I have bigger issues now than the lack of lights ( a tach would be nice though!) Time for a new thread in engines

 

[BADAZ chevy guy]

Not at all, I would have probably gone looking for one. I have bigger issues now than the lack of lights ( a tach would be nice though!) Time for a new thread in engines

Speaking of tacks. I don't remember who sent me this link, but it's where I'm going to get a tach when I get to that point. >>> http://www.classicindustries.com/1979/truck/parts/5659232.html

 

[flyboy1100]

Speaking of tacks. I don't remember who sent me this link, but it's where I'm going to get a tach when I get to that point. >>> http://www.classicindustries.com/1979/truck/parts/5659232.html

nice. what about the fuel gauge? where would that go

 

[BADAZ chevy guy]

nice. what about the fuel gauge? where would that go

The fuel gauge goes where the clock is now

 

[flyboy1100]

The fuel gauge goes where the clock is now

need a different printed circuit board though? i did just find that on the classic industries site.

 

[chengny]

Check the fusible link at the firewall junction block. It supplies the entire left column of the relay block.

This bank includes the fuse for the horn relay and dome/cargo light circuits (20A HORN/DM). It also feeds the two fuses directly under the HORN/DM fuse on the panel (i.e. the 20 A T/L CTSY and the 10A ECM).

The reason the fuse socket is dead for the panel lighting is because there is no power coming back from the rheostat in the HL switch.

The flow goes like this:

The red 3.0 wire from the firewall fusible link is tied into the line side of the far left column (looking forward). The actual connection is in the lower half, there is a shunt about halfway up that supplies the sockets in the upper half. These sockets are for various options (clock, cargo light, etc) that require constant battery power.

Power comes out of the TL/CTSY fuse and up to the HL switch on the .8 orange lead. The voltage is reduced as needed by the rheostat, and is lead out of the HL switch at pin 44. It goes back to the fuse block (from the HL switch) on the 1.0 green lead.

That 1.0 green lead is tied into the fuse block at the hot side of the 5A Inst Pnl fuse. The load side of the fuse is connected to the panel illumination lighting via a .5 gray wire.

Probably the easiest place you can start ringing this out at the HL switch:

Power in to the rheostat on the .8 orange at pin 40 but no power out on the 1.0 dk green at pin 44? Bad rheostat.

Power at pin 44 but not at the line side of the instrument light fuse? The green 44 wire is broken/disco'd.

If there is no power into the rheostat on the orange wire, check the load side of the TL/CTSY fuse. Power there? Broken orange lead from the fuse block to the HL switch.

No power on the load side of that fuse? Check the fusible link.