did the dash wiring in my truck today

[1tonchevy]

was finaly warm enough to tear my dash apart and put the new harness in everyhting sees to work ok but a few little things.

-head lights don't work now?
-oil press guage is pegged wide open?
-some of the cluster lights work some don't tested the bulbs an most of the ones that "don't work" acutally do work?

Other than these little things i'm super pleased with the truck now that i have guages that work!

Any help would be great!

Just took a look at the printed circuit there is a break in one of the prints (it goes to a light bulb but near the oil press guage) might be the prob will look more into it.

also my light switch is broken (the piece inside and the housing) going to get another one tomoro.

[1tonchevy]

anyone?

[75ChevyGuy]

Try cleaning the contacts on the back of the circuit board?

[1tonchevy]

Originally Posted by 75ChevyGuy

Try cleaning the contacts on the back of the circuit board?

the printed circuit? it's at the radio shop getting repaired. he will clean and test it all.

[dropd80s]

Originally Posted by 1tonchevy

was finaly warm enough to tear my dash apart and put the new harness in everyhting sees to work ok but a few little things.

-head lights don't work now?
-oil press guage is pegged wide open?
-some of the cluster lights work some don't tested the bulbs an most of the ones that "don't work" acutally do work?

Other than these little things i'm super pleased with the truck now that i have guages that work!

Any help would be great!

Just took a look at the printed circuit there is a break in one of the prints (it goes to a light bulb but near the oil press guage) might be the prob will look more into it.

also my light switch is broken (the piece inside and the housing) going to get another one tomoro.

If your head light switch is broken I would guess thats why your headlights don't work?

If the oil pressure is pegged out, I think its shorted to ground. Unplug it at the sender and see if the gauge moves, if it does i would guess the sender is bad. If it does not move check for ground short on the wire coming from the sender. If it checks out, I would guess the guage is bad.

If the circuit for the lights in your printed circuit are broken I would guess that why they aren't working? There are little terminals on the plastic sockets that hold the bulbs in the cluster, make sure these are not broken and that they make good contact to the exposed part of the circuit. Some times you have to kind of work them back and forth to make sure they are contacting the ciruit really well. If you can get to them while the HL switch is on you can watch for the bulbs to come on as your messing with them. If some of them are on, you have power to the circuit itself just have to make sure your connections are good and no breaks inline some where.

It sounds like you answered a lot of your own questions, but thats all i can guess based off the info you've listed. There are a million different things that can cause any or all of your problems. Might make sure all your grounds at the ground junction block up high on the kick panel behind the cluster are grounding well. What was your source for your new harness? if another truck are you sure it was a comparable year?

[1tonchevy]

Originally Posted by dropd80s

If your head light switch is broken I would guess thats why your headlights don't work?

If the oil pressure is pegged out, I think its shorted to ground. Unplug it at the sender and see if the gauge moves, if it does i would guess the sender is bad. If it does not move check for ground short on the wire coming from the sender. If it checks out, I would guess the guage is bad.

If the circuit for the lights in your printed circuit are broken I would guess that why they aren't working? There are little terminals on the plastic sockets that hold the bulbs in the cluster, make sure these are not broken and that they make good contact to the exposed part of the circuit. Some times you have to kind of work them back and forth to make sure they are contacting the ciruit really well. If you can get to them while the HL switch is on you can watch for the bulbs to come on as your messing with them. If some of them are on, you have power to the circuit itself just have to make sure your connections are good and no breaks inline some where.

It sounds like you answered a lot of your own questions, but thats all i can guess based off the info you've listed. There are a million different things that can cause any or all of your problems. Might make sure all your grounds at the ground junction block up high on the kick panel behind the cluster are grounding well. What was your source for your new harness? if another truck are you sure it was a comparable year?

Thnaks for all the info. yeah i did answer most of my own stuff but just incase what i'm doing dosn't work i will have more options to try after.the truck i got it from was an 86 mines an 84 81-87 are compatible (so they say)but like i said everything works but those three little things. looks like i got some stuff to try today and a junk yard run! Wish me luck!

[1tonchevy]

new light switch and still nota...head lights will not come on. and they worke b4 i swapped the dash harness. is there a fuse for the head lights? i can seem to locate it on the fuse panel and pulled all the fuses an all see to be good.

Also got my cluster back same thing

[dropd80s]

I do not think the HLs are "fused" at the box. They get direct power through the fuseable links out side. Get you a manual so you can understand the headlight circiutry and start tracing. As I said, the bulbs in the cluster can be fickle. Break out the testlight or multimeter, most problems are really simple fixes.

[ont_guy_38]

what year is the harness from?

[ont_guy_38]

Checked into it , thought maybe cuz the dimmer switch was on the floor it might be different from an older model but they are the same , without the dimmer switch telling the headlight which beam to power up the headlights will not work

[1tonchevy]

Originally Posted by ont_guy_38

Checked into it , thought maybe cuz the dimmer switch was on the floor it might be different from an older model but they are the same , without the dimmer switch telling the headlight which beam to power up the headlights will not work

the dimer switch as in the hi/lo switch?

[78cheyenne292]

check your fusable links off the firewall (thin section of wire just before the firewall under the hood the wire is thinner inside to act as a fuse)just check for power before and after the firewall and if theres no power under the hood it probably your links and yes the hi/low swith

[1tonchevy]

Originally Posted by 78cheyenne292

check your fusable links off the firewall (thin section of wire just before the firewall under the hood the wire is thinner inside to act as a fuse)just check for power before and after the firewall and if theres no power under the hood it probably your links and yes the hi/low swith

lights are back on now.the plug on the lower left side of the colloum was not in all the way i pulled it out and plugged it back in than checked the lights and they work now. Thanks for all the tips on getting them fixed also got a manual now! now for all the dash lights and il guage and were good to go

been playing with the oil press guage took the tan wire off the sending unit grounded it to see if the guage moves... when my test lights hooked up to the batt ground and i touch the tan wire it comes on so the wire is live? i thought it was a ground?

[1tonchevy]

So i think for my dash lights i'm just going to get LED's and make my own lighting.

as for the oil press guage i for got to mention when the trucks off it only goes to the half way mark and wont go back to the start.

[dropd80s]

No the tan wire is 12V. The sender varies the resistence to ground which gives you your different readings on the guage. With the guage dissconnected the guage should read "0", if your touch the wire to ground it should peg out. Keep in mind if that wire has chaffed and is, even slightly, touching bare metal it will show a different reading. 9 times out of 10 its the sender.

[1tonchevy]

Originally Posted by dropd80s

No the tan wire is 12V. The sender varies the resistence to ground which gives you your different readings on the guage. With the guage dissconnected the guage should read "0", if your touch the wire to ground it should peg out. Keep in mind if that wire has chaffed and is, even slightly, touching bare metal it will show a different reading. 9 times out of 10 its the sender.

ok so i'll grab a sender an try it i guess and see what happens.

[TheWhiteElephant]

I would definitely check your grounds first.

[dropd80s]

Originally Posted by 1tonchevy

ok so i'll grab a sender an try it i guess and see what happens.

I would do a little checking first. I'm definitely not suggesting throwing money at the problem, but its your truck man.

[1tonchevy]

Originally Posted by TheWhiteElephant

I would definitely check your grounds first.

What gounds?...just every ground on the truck?

[SeanPaintsFlames]

I think the circuit grounds to the block. Power comes into the gauges, out to the sender, and the sender gives it a limited amount of ground, giving the gauge a limited reading. If it gets a full ground somewhere before the sender, it just thinks it's "wide open". I'd look for a wire rubbed against metal somewhere between the gauge and the sender. Like, through a hole without a grommet sort-of-thing.

I guess if the sender itself is bad it could read full. I always thought they wouldn't read anything if they were broken...?

[TheWhiteElephant]

Originally Posted by 1tonchevy

What gounds?...just every ground on the truck?

Yes, I would check every ground on the truck. There really aren't too many. I had some crazy issues on my taillights. They were working all wacky. I replaced all the switches I could find, and I narrowed the problem down to bad grounds on both taillamps.

The taillamps on my '73 K20 have one ground to the left inner bedside. When I rebuilt the taillight harness, I made 1 ground per side and grounded them to each inner bedside, and then from the same bolt I ran a wire down to the frame and all was solved.

You should have the taillamps ground to the bed, a ground from the bed to the frame, battery (-) to alternator bracket or engine block, radiator support to frame, headlamps to radiator support, firewall to engine head, engine cluster to dash frame, and some others I probably forgot.

One thing I learned in my quest is that if the issue is a crazy one, it is likely a bad ground.

M

[1tonchevy]

Originally Posted by TheWhiteElephant

Yes, I would check every ground on the truck. There really aren't too many. I had some crazy issues on my taillights. They were working all wacky. I replaced all the switches I could find, and I narrowed the problem down to bad grounds on both taillamps.

The taillamps on my '73 K20 have one ground to the left inner bedside. When I rebuilt the taillight harness, I made 1 ground per side and grounded them to each inner bedside, and then from the same bolt I ran a wire down to the frame and all was solved.

You should have the taillamps ground to the bed, a ground from the bed to the frame, battery (-) to alternator bracket or engine block, radiator support to frame, headlamps to radiator support, firewall to engine head, engine cluster to dash frame, and some others I probably forgot.

One thing I learned in my quest is that if the issue is a crazy one, it is likely a bad ground.

M

ok thanks guys i'll start y seach once i get a nice day out and let you knwo what turnes up

[csb#356]

Also check where the printed circuit grounds under the dash

[1tonchevy]

Originally Posted by csb#356

Also check where the printed circuit grounds under the dash

is that the one that mounts just behind the dash on the driver side?

[csb#356]

Yes its mounted to the bracket for the parking brake (on my 77 anyway)