Gauge Cluster Issues, Where to start?

[D-n-Tyke]

So final got the truck up and running and am now trying to figure out this gauge cluster. Have the temp gauge, fuel gauge and the amp gauge hooked up. Speedo and oil pressure are not connected so of course those are not worrying at this moment.
The 3 hooked up gauges, temp, amp and fuel, all seem to be working, along with the both green arrows for the directionals. The problem I am having is when either of the directionals are turned on, the gauges go crazy. The temp gauge sweeps to pegged and then back to normal at the beat of the flasher. The fuel gauge stops working and slowly goes to empty. As soon as the directional is canceled things go back to normal. Additionally, when I turn the headlights on I loose all the gauges. I thought it might be a bad ground but I checked the ground where it attaches to the back of the metal dash and where the wire goes into the harness connector and have solid ground at both locations.

I am not sure where to go from here. What to check next. Has someone else had this similar issue and what was the solution that fixed it.

[Steeveedee]

Is the panel grounded properly?

[pjmoreland]

Like Steeveedee asked, is your metal dashboard grounded properly? Do you have grounding straps installed between your firewall and engine?

[body bolt]

...and is that connector plugged in the correctly?

[michael bustamante]

are you using oem guages or aftermarket?

[D-n-Tyke]

Okay, I will try and answer all these questions.

Metal dash is grounded. This was testes using my power probe to verify there was ground there all the way back to the battery. Clip on the dash shows solid ground. Ground wire into the connector shows ground back to the battery.

Don't currently do not have a ground strap from the engine to the firwall. I will add one and see if that changes anything. However, as said above, my probe shows there is solid ground from the metal dash to the battery, so I am going to assume that the engine to firewall isn't going to fix this.

Gauges are the OEM gauge cluster.

Best I can tell connector is pligged in correctly and fully seated.

[dmjlambert]

Was the truck made for a warning light instrument cluster, and now you're putting a gauge cluster in it? If so, the plug is pinned wrong.

[D-n-Tyke]

Ground strap added from block to firewall. No change in issues.

[too much stuff]

Originally Posted by dmjlambert

Was the truck made for a warning light instrument cluster, and now you're putting a gauge cluster in it? If so, the plug is pinned wrong.

Check this...

[D-n-Tyke]

Originally Posted by too much stuff

Check this...

As far as I know the cluster is the original cluster. It was there when i bought the truck and looks to have never been removed.

[D-n-Tyke]

Reviewing the full wiring diagram post on here, the connector is pinned out as shown for the cluster with gauges.

[dmjlambert]

OK, good. Next is do the buckets for the front parking lights/turn signals have a good ground? Do you have any LED bulbs installed in the truck such as in the front marker lights or front parking lights/turn signals?

[D-n-Tyke]

Originally Posted by dmjlambert

OK, good. Next is do the buckets for the front parking lights/turn signals have a good ground? Do you have any LED bulbs installed in the truck such as in the front marker lights or front parking lights/turn signals?

Are you talking buckets in the turn signals themselves (ie in the front grille (1969 truck) or the buckets in the cluster?

There are no LED bulbs in anything. All OG filiment style bulbs.

[dmjlambert]

Yes, buckets in the turn signals in the front grille need to be grounded. If not, you'll get wacky goings on. I don't know for sure about the specific wacky things you have going on, but some wackiness nevertheless.

[dmjlambert]

Did you paint the metal parts of your instrument cluster? 2 of the screws that go through the printed circuit need to be good grounding points for the printed circuit traces.

[D-n-Tyke]

Originally Posted by dmjlambert

Did you paint the metal parts of your instrument cluster? 2 of the screws that go through the printed circuit need to be good grounding points for the printed circuit traces.

Gauge cluster is original patina. Hasn't been painted.

[pjmoreland]

Do you have the two screws installed in the upper back of the gauge cluster that ground the flexible circuit board to the metal case of the cluster?

[D-n-Tyke]

Resurrecting this post to post what I found incase it can help someone else in the future.

Finally was able to dig into this, and after triple checking all the wiring and dash groubd lead, went ahead and pulled the gluster. Found a break in the ground trace in the printed circuit. Solder a jumper across the break and all is back to working like normal.

Only small disappointment is all the gauges light up bright, except the battery gauge. It seems to be about "half" lit. Right side is lit up, left side is dark. I replaced all the bulbs with new 168 bulbs so don't know if this is normal, or if I should be looking for something to cause it to be dimmer then the rest.

[pjmoreland]

Nice satisfying find there.

Only four of the bulbs are for backlighting. With the lights on, reach up under the dash and twist one of the bulb sockets at a time to disable it. You should see diminished light for each bulb you twist. If you don't see diminished light, then that's your culprit. The bulb socket contacts tend to get crusty. Pulling the bulb out of the socket and reinstalling it 10-20 times can help. The socket that is above the battery gauge is the most likely suspect.

[dmjlambert]

Good solder repair. If you get flexible and just decide you're going to contort, you can get to where your hand is acquainted sticking up in the dash, identifying by feel and working with those sockets. In the dark. While looking at the dash to see what's lit. :-)

[D-n-Tyke]

Originally Posted by pjmoreland

Nice satisfying find there.

Only four of the bulbs are for backlighting. With the lights on, reach up under the dash and twist one of the bulb sockets at a time to disable it. You should see diminished light for each bulb you twist. If you don't see diminished light, then that's your culprit. The bulb socket contacts tend to get crusty. Pulling the bulb out of the socket and reinstalling it 10-20 times can help. The socket that is above the battery gauge is the most likely suspect.

Finally was able to get out there in the dark tonight and check the bulb above the battery gauge. Bulb was fine. Turned out to be a bad bulb socket. Luckily have a couple extra. Swapped it out and all is good. All gauges are nice a bright now. Thanks for the guidance.