97 jimmy 4x4.. Mater
 

Ive got a crazy problem with the gauge cluster.
cant get the lamps on the right side to work and gas gauge seems to be unfixable... ugh.
Ive bought 4 instrument clusters now, found a fuel level buffer control module and even swapped gas servo, twice...im ready to pay somebody

Let's try to break down to bits and pieces to solve your problems. First what is your fuel gauge doing? Is it stuck on empty or full? This may help narrow down the problem overall. A bad ground will register "FULL" on your gauge. A short to ground will indicate "EMPTY" on your gauge. This may all come back to a wiring problem or a component problem l.E. bad ignition switch. So to start, what is your fuel gauge doing?

Fuel gauge cluster f..
 

at present. It reads full.
Just b4, it would act spastic and when steady. It read 1/4 tank which i think was accurate.
i found a fuel level buffer control module in michigan from s10 forum member. That stopped the bouncing, spastic routine and now reads full..
my 97 gmc jimmy, 4.3L is fresh, and the only year gm did this particular setup...
Ive rwad continuity on the wires to and from pump, all good and grounded... i did add 10 gals of gas. So, not sure if full or not. I doubt it

So when you say you installed a "buffer module" are you referring to the fuel sending unit on top of the pump? Gauge bouncing around indicates the buffer inside the sending unit is bad, which can be due to a pump replacement with an aftermarket pump (non AC Delco or Delphi). Did you replace the pump or do you know if it was replaced?

EDIT: You can still show continuity with a bad/corroded ground. Continuity doesn't indicate if you have high resistance.

EDIT2: Just looked at my '97 manual and saw there is a separate module (no longer have that truck). Disregard what I stated about the module. But the manual does state that FULL can indicate a bad ground.

Ibe found that 97 is the only year 4 this "slush" card. It receives signal from (1). Oil pressure sensor, (2). Fuel sending unit..
its exposed right now, but lives below and behind glove box.
My skills with a volt meter above avg. Electrician here. I think im loosing that single circuit to OR from pcm...
And as electrician, im absolutely stumped with this issue. Makes me feel stupid with 2 o's
https://cimg6.ibsrv.net/gimg/blazerf...d009ea9e3f.jpg
B4
https://cimg8.ibsrv.net/gimg/blazerf...70c60f3553.jpg
After

As you are an electrician, take a look at below and see if it seems like a direction you might want to go:

Went thru the schematic trying to find the easiest place to put a temporary fused ground jumper wire before taking anything apart to see if you have a ground problem. There are also grounds at the back of the truck in case it's a sender problem, but since you are having a cluster problem also, went that direction first.

The ground I'm referring to goes thru a couple splices in the passenger compartment and then goes to a roundish connector above the brake booster in the engine compartment (#6 in the image). You could first disconnect that and look for any green crusties.

If connector looks good, reconnect it and I would try backprobing pin "B" (circuit #150) in the connector with a T-pin (place pin carefully) and a fused jumper wire to a good ground (personally I would use a long wire all the way to Battery(-) post for this test). You could also shave some insulation off #150 wire to connect jumper wire, but insure you seal it very well with liquid tape. I don't like to do that unless absolutely necessary.

If no change, grounding problem could mean taking some interior apart, but you've knocked out where it isn't.

Also note this is a '97 Blazer manual and is a reference. If you don't have a Jimmy manual, go to Alldata.com and buy an online subscription (they have easier wiring diagrams than a manual) for your truck to insure circuits and pins in the connector are the same. I think they are, but I wouldn't swear to it. I suggest using manual/schematics for your specific truck, just in case.

Note: The top part of the page for the connector is for a 2.2L, ignore that. If you want the rest for the 4.3, I can post that.

https://cimg9.ibsrv.net/gimg/blazerf...14894f4606.jpg
https://cimg1.ibsrv.net/gimg/blazerf...522d5d9379.jpg

Note the illum lamps also ground on circuit #150.
https://cimg5.ibsrv.net/gimg/blazerf...81809f4477.jpg

My mistake, illum are ground "150". "151" Connector terminal "K" for fuel gauge ground.

https://cimg4.ibsrv.net/gimg/blazerf...e0770b0794.jpg
https://cimg7.ibsrv.net/gimg/blazerf...48eee32cca.jpg

Gotcha, to be clear, ima put a fused ground shot on pin 'b' at connector 6, and that should move the needle.
i can pull the cluster (again) and read those pins w/key on.
At the ecm. The 4 diff color bundles going i/o of ecm... mine were never labeled. Would you have that layout?
please and thank you

Btw, its the center lamp on a straw and the 2 lamps on the right now working..
i have continuity to all landmarks, pos and negative....feeling stoopid.
Like maybe, looked at this mess for 2 long, its gotta be sumpin simple, im just burnt on it