instrument lamp power and ground

[ratvon]

Where do the lights for the instrument cluster get their supply and ground from I got a schematic but isn't much help for me. I took my dash out and refurbished everything, got it all laid out and the all the harness' hooked up so I can check every thing and got power to every fuse except the instrument lamps. To me it looks like power comes from the headlamp switch and from the alt. before that. Does the dash need grounded to my battery because nothing works but I got juice to the fuses, (except the instrument fuse no power at all there).

thanks Rob

 

[mderoy340]

if I remember correctly power comes from the light switch in park or on, goes thru the fuse to panel lts. ground is from bezel mount screws to dash, best to run/add a dedicated ground.

 

[ratvon]

ok how and where?

 

[67Dart273]

1.............What year / model?

2............Go here and download a free factory manual

http://www.forabodiesonly.com/mopar/showthread.php?p=1970088617

More stuff here

http://www.mymopar.com/index.php?pid=31

Here's how your light switch and instrument power works.

First, there are TWO sources of power FEEDING TO the light switch. On most these cars, a branch off the big black ammeter wire up under the dash feeds UNFUSED power to B1 on the switch. This supplies ONLY the headlights, which have their own breaker built into the switch

Park, tail, and instrument power goes TO the headlight switch B2 from the tail fuse. This B2 powers tail, park, and instrument lamps

This is a bit of a trick. Instrument (dash dimmer controlled) lamp power goes through the dimmer control, TO the instrument fuse (tan) and THEN through the instrument fuse, and OUT to all dimmer controlled dash lamps on ORANGE

So the instrument fuse will ONLY have power if..........

The tail fuse is good...........

The tail light circuit works.........

The light switch must be in either park or head

The dash dimmer is "twisted somewhat left" to brighten the lamps

ONLY THEN will the inst. fuse show power

So far as your cluster it MUST be grounded. It would behoove you to go through the cluster if you have not

1.....Add a ground wire trace out the PC board and find a ground screw trace and add a pigtail wire. Bolt this to the dash frame or column support

2....Check for broken harness connector pins or bad connections at them. Repair as necessary

3....On my Dart, the "plug in" socket for the instrument regulator, the brass contact fingers were not making contact with the actual board traces. Solder jumpers across

4....Replace the old unreliable IVR with a modern solid state one. There are several outfits that sell them

5.....Loosen / tighten the fuel and temp gauge nuts several times to "scrub" the connections clean, and consider replacing the "fake" nuts with real nuts

6.....Clean the PC board where the sockets twist in.

7....Clean up or replace the sockets. Bend the fingers for better contact. Replace the bulbs or "go LED," LOL

This would be a good time to "jimmy" up the cluster to power and check that the gauges actually "sort of work." You can do this with clip leads. Substitute test resistors for the senders. "Full" is about 10---13 ohms, "1/2" is about 23 -- 25 and "empty" or "cold" is about 70--75 ohms. Leave the gauges hooked up for at least 1 minute for testing. You MUST have a proper working instrument regulator for this test.

 

[ratvon]

Its a 68 barracuda

 

[ratvon]

Where the instrument lights ground on the circuit board I ran ground wires everything seemed good on the bench now in the car only a few lights work and very weak plus my ground wires I made I run to my dash mounting bolt and it's showing power like a short. ....is it chasing a ground? It will actually pulse and get brighter when I turn the hazard switch on

 

[72Valiant4Door]

Beautiful post.

1.............What year / model?

2............Go here and download a free factory manual

http://www.forabodiesonly.com/mopar/showthread.php?p=1970088617

More stuff here

http://www.mymopar.com/index.php?pid=31

Here's how your light switch and instrument power works.

First, there are TWO sources of power FEEDING TO the light switch. On most these cars, a branch off the big black ammeter wire up under the dash feeds UNFUSED power to B1 on the switch. This supplies ONLY the headlights, which have their own breaker built into the switch

Park, tail, and instrument power goes TO the headlight switch B2 from the tail fuse. This B2 powers tail, park, and instrument lamps

This is a bit of a trick. Instrument (dash dimmer controlled) lamp power goes through the dimmer control, TO the instrument fuse (tan) and THEN through the instrument fuse, and OUT to all dimmer controlled dash lamps on ORANGE

So the instrument fuse will ONLY have power if..........

The tail fuse is good...........

The tail light circuit works.........

The light switch must be in either park or head

The dash dimmer is "twisted somewhat left" to brighten the lamps

ONLY THEN will the inst. fuse show power

So far as your cluster it MUST be grounded. It would behoove you to go through the cluster if you have not

1.....Add a ground wire trace out the PC board and find a ground screw trace and add a pigtail wire. Bolt this to the dash frame or column support

2....Check for broken harness connector pins or bad connections at them. Repair as necessary

3....On my Dart, the "plug in" socket for the instrument regulator, the brass contact fingers were not making contact with the actual board traces. Solder jumpers across

4....Replace the old unreliable IVR with a modern solid state one. There are several outfits that sell them

5.....Loosen / tighten the fuel and temp gauge nuts several times to "scrub" the connections clean, and consider replacing the "fake" nuts with real nuts

6.....Clean the PC board where the sockets twist in.

7....Clean up or replace the sockets. Bend the fingers for better contact. Replace the bulbs or "go LED," LOL

This would be a good time to "jimmy" up the cluster to power and check that the gauges actually "sort of work." You can do this with clip leads. Substitute test resistors for the senders. "Full" is about 10---13 ohms, "1/2" is about 23 -- 25 and "empty" or "cold" is about 70--75 ohms. Leave the gauges hooked up for at least 1 minute for testing. You MUST have a proper working instrument regulator for this test.

 

[67Dart273]

Where the instrument lights ground on the circuit board I ran ground wires everything seemed good on the bench now in the car only a few lights work and very weak plus my ground wires I made I run to my dash mounting bolt and it's showing power like a short. ....is it chasing a ground? It will actually pulse and get brighter when I turn the hazard switch on

I hope you did not hook the ground to the ammeter? (Big RED and big BLACK, neither are ground) You post a photo of where you hooked it?

Does it get brighter with the hazard, when grounded with the extra wire?

Finally if the cluster is "hanging out" IE for testing it MUST be grounded. The mounting screws are the only OEM ground

 

[ratvon]

I didn't ground it to the ammeter ,I'll try to get a picture and yes when the hazard switch was on there was more juice going to the wire I added