Gauge cluster repair

[Gunner41]

Morning all,
So Im trying to find a place to repair my gauge cluster over here in Silicon valley Ca.
Yeah it seems unless my truck is a new 00 on up the old school professors moved out and the students here only know 1. How to swap parts without diagnosing. 2. Only touch NEW vehicles.
If somebody has a place in mind, please let me know. Im tired of looking and need to pull my hydrobooster off and rebuild it so I figured if its just going to sit there might as well get it done.

[sntrym95]

From my experience, you're probably going to have to ship it somewhere. There was a place locally here in Cleveland that would ship it to somewhere in FL a while back. They are closed up now, so Google is going to be your best bet.

I keep a spare one from the boneyard around just in case, and depending on what's wrong with yours you could pick one up from the boneyard or Ebay and swap the odometer over.

[hatzie]

What seems to be wrong with the cluster?
The T400 clusters used air core movements that were generally quite reliable. Usually the problems I've found are not the instrument panel.
A half decent gauge tech can add damping fluid to tired air core gauges to stop the needles from flopping around.

[Gunner41]

1. The fuel sort of went bonkers and its off by about 1/4 tank which i can deal with but it would be nice especially with the 35 gl tank.
2. The temp always says its overheating even tho I know its not. I added a mechanical and plumbed it into the R/S head and my OBD II live data shows it hits 195-197 on average but has hit 200 so i marked 195 on the mechanical. The cluster says 230 so no its wrong.
Now for the annoying one. My oil pressure has dropped years ago it showed 5-15 PSI and so I verified that really it was good. I replaced the pump to a Melling high volume pump and steel one piece shaft when I had the pan off and also verified that it works with another mechanical gage. Sorry im long winded. The other day I heard a grinding sound then the gage shot up full blast and goes all the way up when I run the truck. Ugh
Oh its my 3500 7.4

[Mr_Rich]

There's a big difference in 88-91 gauge cluster vs. the newer ones. I found that the hard way. My 89 uses a circuit board while later gauge cluster uses the thin plastic with conductors sandwiched in. Which one do you have? My speedo and oil pressure act up and I give the cluster the "Fonzie" rap with my knuckle to get it going. I tried soldering the circuit board but that didn't quite do the trick. I worked Telco for thirty years so I know soldering.

[hatzie]

The fuel gauge is usually the sender not the gauge. The fuel gauge itself is run from the ECM. The fuel sender wiring is a loop from 5v reference to the fuel level sense terminal on the ECM.

The GMT400 still uses two temp senders even in the end of production 2000 model year trucks. You should have an ECM temp sensor and a gauge sensor. IIRC the gauge sender is in the LH cylinder head and the ECM sender is in the intake.
Just because the ECM knows the engine temp doesn't mean the gauge sender or wiring isn't knackered.

[Gunner41]

I actually changed them both (After I found out about the intake one) it didn't make any difference. To be extra certain We tested ALL of the sensors out of the vehicle as well. Turns out that I didn't need to replace them and couldn't take them back.
I appreciate the help Sir. Im actually have to not work on this now anyway. My Hydro boost sprang a leak and in the disassembly process I found out that mine does not have a Check valve ball/rod and further research says that I should and of course I found diagrams with them and without them. I'm trying to find a way to ID the individual unit. Sorry I didn't mean to drag on with a different issue.

Thanks again Sir