Investigating Malfunctioning Oil Gauge in '90 TBI Burb

[89Suburban]

Halp meh

[yt]SJDGQfIaFwk[/yt]

Your gauge is spinning. You either have one helluva oil pressure problem or a bad gauge.

It's been doing that since I bought it. But now tonight it was responding to engine speed. Before I noticed that it was responding to the damn turn signals LOL!

I guess I will have to try the oil gauge from the '89 and if that don't cure it then it has to be in the printed circuit or sending unit?

I bet if I open that cluster up and wiggle that gauge it will start working normally.

Likely, might be an intermittent connection at the cluster terminals.

Or a bad ground.

While Yuhr in there, pull them little clips out and clean them up and pinch then down a bit tighter. that seems to keep the guages in My truck a bit more honest. Keeps um from runnin in circles too.

So the first thing I should do is pull the cluster and check the plug sockets for the gauge and printed circuit right? And fire it up with the cluster hanging and if'ts still bouncing I can try the gauge of the '89?

I wish there was a troubleshooting check list for this.

 

[chengny]

To review:

Variable voltage type gauge theory of operation - just as general information:

VARIABLE VOLTAGE TYPE
The variable voltage type dash gauge consists of two magnetic coils to which battery voltage is applied. The coils act on the gauge pointer and pull in opposite directions. One coil is grounded directly to the chassis, while the other coil is grounded through a variable resistor within the sending unit. Resistance through the sending unit determines current flow through its coil, and therefore pointer position.
When resistance is high in the sending unit, less current is allowed to flow through its coil, causing the gauge pointer to move toward the directly grounded coil. When resistance in the sending unit decreases, more current is allowed to pass through its coil, increasing the magnetic field. The gauge pointer is then attracted toward the coil which is grounded through the sending unit.
A special tester is required to diagnose this type gauge. Follow instructions included with the tester.

Gauge failures are often caused by defective wiring or grounds. The first step in locating trouble should be a thorough inspection of all wiring, terminals and printed circuits. If wiring is secured by clamps, check to see whether the insulation has been severed, thereby grounding the wire. In the case of a fuel gauge installation, rust may cause failure by corrosion at the ground connection of the tank unit.

Basic schematic. Note: this is applicable to all dash indicators (i.e. gas tank level, coolant temp, oil pressure):

 

[chengny]

Here is a half-assed diagram I made to try to demonstrate how the gauge actually reacts to the two resistances (variable through the sensor and straight to ground):

You must be registered for see images attach

It shows a coolant temp sender/gauge but the oil pressure indication is the same.

If your oil pressure gauge is sporadically jumping up to the pegged high end - it would indicate a short to ground in the sensing lead that goes to the 0-60 sender. I think it's a tan wire.

 

[89Suburban]

Thank you sir


Posted From Hell

 

[89Suburban]

Jerry I apprecaite the info, it turned out the gauge was bad. I put the gauge in from the 89 and it works beautiful.

 

[bucket]

I guess that means your oil pressure is good then too. Otherwise I don't think we would see dancing bananas from you.

 

[RetroC10Sport]

Whadyano, I wuz rite!

 

[89Suburban]

Whadyano, I wuz rite!