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1988 C1500 RCSB 305 5.0

I noticed that within 30 seconds of being at my house on the way home from work today my Check Gauges light came on. Oil pressure dropped to zero and stayed there, but would bounce up to the 1/4 mark on the recrank with some gas.

Cluster problem? Oil pressure sending unit perhaps? And my water temp gauge went out as well, but is buried hot, so I figure that is a cluster problem at most.

How can I go about diagnosing the problem and fixing it, short of replacing parts until it is fixed, which could be pricey I'd imagine.
 

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Gauges on GM trucks going bad, or crazy, are not usual. The sending units go bad quickly, as well. I'd check the units before saying the cluster is trash. Sending unit for the temp gauge is cheap and easy to install.
 

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Yeah, I bought the sending unit for the temp guage, but havent bought the coolant I need to refill after I install the sending unit. That's just me being lazy, lol.
 

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1988 C1500 RCSB 305 5.0

I noticed that within 30 seconds of being at my house on the way home from work today my Check Gauges light came on. Oil pressure dropped to zero and stayed there, but would bounce up to the 1/4 mark on the recrank with some gas.

Cluster problem? Oil pressure sending unit perhaps? And my water temp gauge went out as well, but is buried hot, so I figure that is a cluster problem at most.

How can I go about diagnosing the problem and fixing it, short of replacing parts until it is fixed, which could be pricey I'd imagine.

Pull the sender wire at each sensor (single wire) and turn the key on. Each gauge should be at an extreme. Ground each wire and each gauge should sweep to the other extreme. Only do this with single senders. The two wire senders, if there wires are grounded, can cause computer problems.

The temp is under the driver's side manifold with a single dark green wire. slide the black cover in the direction of the wire.

The oil pressure wire is slid on the barrel sensor pointing at the driver, next to the distributor. It is a female bullet connector and, IIRC, the wire is brown.
 

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Well, I replaced the Oil Sending Unit today since it only costs $20 new. From the crank it seems alright. It wasnt sitting below 45 like it usually did and from the quick run it didnt appear to want to bounce.

I guess the true test will be the ride to work tomorrow. Hopefully this solved it.

Thanks for the replies fellas! Now I just have to change the temp sending unit.
 

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Glad it seems to be going well. Be ready to lose some coolant when swapping it out. do it fast enough and it shouldn't be much.
 

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If you're still having trouble, ensure that the ground wires are still attached at the rear of the passenger cylinder head.:bowtie:
 
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