Erratic gauge cluster need some help

[1997XLTRollover]

Hey guys, as usual this is on my 96, the truck I should have scrapped. I'm getting a jumpy temp gauge and fuel gauge. I also had a twitchy or incorrect reading alternator gauge also at one point but that now seems fine. I randomly get the check gauge light on for a second and then it turns off. I thought at first my fuel sending unit was bad so I spent 500 bucks on a tank, pump and sending unit. Well that was a waste because it didn't fix a damn thing.

Thoughts on what might be causing this? Bad instrument cluster maybe? I also have a ce light for evap and I'm thinking the fuel gauge reading wrong is screwing up the evap test.

 

[1997XLTRollover]

Bump. Anyone? Maybe someone with a wiring diagram that can check ground paths to see which ground may tie into all of these issues?

I did notice something odd and that is that my check gauge light seems to come on when I come to a stop and almost never when driving, although it does happen on occasion. I'll come to a traffic light, start slowing down and when I come to almost a complete stop, my check gauge light pops on and fuel and temp gauges start going wacky. Start driving again and they calm down, still moving around a little bit but not as bad.

I also realized some issues with my power locks recently. I'll hit lock or unlock and all will lock or unlock but 1 door. Her's the kicker. It's not the same door every time. I hit unlock and then lock again and it will be fine. I also remembered that when I start my truck and first start driving my ABS pump activates for a split second and then never does again until I restart the truck. I feel like I have some electrical gremlins and cannot figure this out. I'm coming up on my inspection deadline fast and have to get this figured out.

 

[swshawaii]

Test the BATTERY first, alternator second, especially when having various and intermittent electrical issues.

ALL connections and grounds checked?

 

[1997XLTRollover]

Test the BATTERY first, alternator second, especially when having various and intermittent electrical issues.

With the truck off the battery reads 12.5-12.6 volts. Running it reads 13.9-14. Is this what you mean by test?

 

[1997XLTRollover]

Ok well crunch time is here because I'm going to fail inspection in August. I went ahead and replace the battery AND the alternator and it made no change. So now thanks to my erratic fuel gauge I have replaced my gas tank, fuel pump, sending unit, battery and alternator. What else can be causing this? Is there some voltage regulator on the back of the cluster that might effect a lot of the gauge operation?

 

[1997XLTRollover]

Could I be missing a ground somewhere? Maybe a frame to body ground? I never recalled seeing where one would have been bolted. Does anyone know where all the grounds are?


Also could my anti-slosh module be bad? Does that module regulate voltage for all gauges or just the fuel gauge? Or is there a separate voltage regulator in the cluster that is maybe bad?

 

[1997XLTRollover]

Well I checked both grounds in the kick panels, pulled the entire dash apart and ripped the cluster out and it looks ok. I cleaned the connections to be sure but there was nothing that looked out of place. Every ground in the engine bay I can find has been cleaned. In desperation I've now bought an instrument cluster to see if maybe the cluster is bad. Pretty soon I will have replaced this entire truck.

Does anybody know if there is a frame to body ground somewhere as well as an engine to body/frame ground? I'm not sure where to find it and I don't see anything anywhere and want to be sure I'm not missing ground straps somewhere. All I see is the intake bolt to firewall ground and the ground cable from the battery to the block and then the small cable to the rad support.

 

[1997XLTRollover]

New Gauge Cluster didn't seem to fix it either. Temp gauge is still flying all over the place. Although the fuel gauge may actually be fixed. I'm keeping my fingers crossed but I'm not very hopeful because I've only put about 8 miles on it. Unless I also have a bad sending unit. Really wish I scrapped this truck 2 years ago before having to dump 5 grand into it in parts just making it run halfway decent. I've basically restored this thing.

 

[1997XLTRollover]

Well I've added grounds to the truck all over and still have gauges that are messed up. My fuel gauge for the moment seems ok but I still have fluctuating Alternator and Temp gauges. I also remembered I actually replaced the temp sending unit when I did the engine. Granted it could be bad but the fact that I have 2 gauges freaking out makes me think it's fine.

The odd thing is, I was at my shop and the gauge was reading low as it does sometimes, so I quick grabbed my meter and it read 14.3 volt charge right on the battery posts. So it seems like the system itself is fine but the gauge is reading wrong. I guess the next step is to check to be sure the proper voltage is coming into the cluster. Does anyone know which wire supplies voltage to the cluster? Mainly the alternator and temp gauges?