Simple check - is the brightness of your dimmer switch up?

Next step, check the contacts on the board for any corrosion, clean up with a pencil eraser.

And check the fuse, like ctubutis says! I always forget the obvious.

If you did this with the battery connected, there's a decent chance you blew a fuse.

 

Aftermarket stereo installed? Make sure the radio dial illumination circut is not being used as a ground wire. Very comon mistake.

 

Ok, checked the fuse and it was good, but replaced it with a new one anyway. The truck DOES have an aftermarket radio in it. I removed the radio and still nothing. Could it be in the wiring for the radio? What wire do I need to look for?

 

Light Blue/ Red Stripe wire.

This powers the instrument cluster lighting, the radio dial illumination for factory radios, etc..

Check the headlamp switch connector. Light Blue / Red stripe wire with the headlamp switch on. you should have power at the switch at this wire. If not, make sure the dimmer is turned all the way to the left, but just before it turns on the dome lamp. Turn the **** like you would a radio ****. If still no power, replace the switch.

Then move down to the fuse panel if you had power at the headlamp switch, check both sides of the fuse etc... then go to the cluster connector.

Basicly trace the light blue/Red stripe wire along it's journey so to speak.

Pretty soon you should come to the problem.

 

I did this swap and now have a factory tach, but it certainly wasn't plug and play - the plugs were different between the tach cluster w/ gauges and my old cluster w/ idiot lights. I didn't cut the old plug off, just soldered the one w/ ~6" pigtail I got from the donor truck onto my existing one - the only tricky part was the resistance wire, but it has a nice 6" lead I assume for testing - sure makes a nice place to solder it up to another plug =) Think the coil lead was there as well, just had to find it.

 

It's only plug and play with ammeter and oil gauges.

Cluster with warning lights is different. You actually should not have rewired that plug without adding an ammeter shunt in the altenator wiring and rewiring the altenator and external voltage regulator wiring. The ammeter is only rated for about 5 amps. The altenator can put out 40 or more amps. It would be a bad thing and cause a fire if 40 amps went through your 5 amp ammeter. If you don't know what I'm saying or didn't do the nessecery circut changes, your truck can be in danger of catching fire.

 

And it's not necessary to cut & solder, either - those wires and connector terminals come out of the plastic connector housing, use a small screwdriver or dental pick to move the little springy, plastic tabs holding each terminal in place and pull it out from the rear.

 

Cool, thanks for the advice. I turned the parking lights on an rotated the shaft so the lights were all the way on and I could see the light thats above the headlight switch get brighter and dimmer, and same for the HVAC controls, so I'm guessing the problem is at the radio wiring. I'll try and trace that out in the morning.

 

Did the original cluster have lights?

 

Nope, same problem on the original one. I tried three sets of bulbs and tested them all and they are all good, but none of them work in the gauge cluster, but work in the turn signals.

 

Thanks 81 - yeah, I should have said the ammeter doesn't work. Once I understood how it was wired with the lead of the alternator running through the dash, and the gauge it'd have to be, I decided to simply install a HF volt meter in the dash and that tells me if I had a functioning alternator. Also had to put a resistive load (light bulb) to get the alternator to turn back on as well once the idiot light was removed, but put that up but behind one of the translucent labels at the top of the dash (think the 4x4 one). When I swap the 300 soon will go with a 1 wire Delco unit to fix that Band-aid.

I still have the original plug there, taped off right beside the new plug. It's been functioning now for over 10 years like this, so think it's ok =)

ctubutis - Now you tell me! =) that seems a lot easier to do that soldering, so if I get to do it again will definitely disassemble the old one like you suggested.

Thanks!

 

With the above information, I would look at the cluster connector. Make sure you have power at the Light/Blue Red wire in the cluster connector. Also check to make sure your printed circut is in good shape where the cluster connector connects to the printed circut.

Also check the cluster connector for a possible broken terminal.

 

Ok, this is just confusing now. I found two things. First, I took the radio out and looked at all the wiring. I found the light blue with red stripe wire coming from the cluster connector, followed it to a harness next to the cluster. It then goes to a pair of black connectors next to the HVAC. The blue/red wire then goes into the HVAC. I see where the previous owner cut the radio wires and wired in the new radio. There are three gray connectors on the right side of the radio. One is disconnected, and the other pair is connected. One side of the connected pair goes to the passenger side behind the dash and glove box, and the other side goes to the new radio harness. On the side that goes to the radio, there is a blue/red wire that is cut, but I can't find where the other end of that wire is or where it would connect to.

Second, here's the weird part. I then put both clusters back in and used the original 194 bulbs. I put the parking lights on and tested each socket on the printed circuit board and with the meter set to DC mA, I saw a reading of 9. With both clusters with a full set of the old 194 bulbs in place, the cluster doesn't illuminate, but I could see a faint glow under the odometer. What the hell? Do I need to find low voltage LEDs to make them brighter?

 

Hmm, this is unusuall.

The Aftermarket radio will not use that Light Blue/Red Stripe wire, so it being cut is understandable, if not the best way to do things. Is there power to this wire?

The other connectors by your HVAC is for the digital clock, and courtesy lamp connectors. Not all trucks have that option.

Since the HVAC controls light up, and the Wiper and Headlamp indicators light up, you have power to the circut.

If you got power to the cluster connector...

I'm thinking it might be a ground fault in the cluster or wiring.

Check the ground to the cluster.

Black Wire, no tracer color.

You can also hook a temporary ground to the instrument cluster voltage regulator. It's a rectangular device hooked on with a 1/4 bolt headed screw. Attach a ground wire to the screw to sheetmetal, with everything hooked up, and report back any changes. This should eliminate the possibility of a bad ground to the cluster.

Also are the light bulb twist sockets that go into the cluster in good shape, making good contact?

 

Ok, after almost a month of tracing wires, testing, and pulling my hair out, I finally figured it out! It turns out with both the original cluster and the new cluster, the blue filters that cover each of the bulbs were so dirty they were only letting like 10% of the light through. I popped all the filters out and viola! Light! Thanks for all the help guys


The one test that led me to the filters was I peeled the circuit board back and with the power to the instrument lights on, I put one of the lights on the board so the contacts made contact and each of the lights worked and were bright. That told me all the wiring was good, the bulbs were good, and the sockets were good, so it had to be something in the plastic cluster housing itself.