Suburban 1996 4x4 2500 7.4 litter my check gauge light comes on after about 1-5 minutes of driving. the check indicator also pops up on the computer dash at same time . the batter voltage meter goes from1/2 charge to zero at the point when the check gauge light my suburban and does not run well

you probably have your finger on the problem. have oil pressure test .when engine hot minimum 12psi.and change the thermostat.Don't cost much

first check battery connections for being loose or corrosion
then if thats not the problem you'll need to check for bcm codes ,ipc codes etc .
these will have to be checked with a hand held scanner

Either the belt has stretched, or the tensioner is not keeping it tight.
Or it has oil on it.

Well it could be the selector switch, but I doubt it.
Generally, the service light means something is not working that the computer controls. Solenoids and valves are a couple of possibilities.
The transfer case is shifted by solenoids commanded by the body computer based on the switch position on the dash.
You should be able to have a shop scan the body computer for trouble codes and proceed from there.
A basic code reader may not access the body computer.

try a manual pressure gauge and see what happens

Have you checked the oil pressure with a mechanical gauge or are you going by the gauge in the suburban. If you're going by the electric gauge in the suburban I would suggest checking it with a mechanical gauge. If the mechanical gauge confirms the oil pressure is low then you probably have a serious engine problem. If the mechanical gauge indicates normal pressure the O/P sender is probably the culprit.

check all grounds

starter solenoid has bad connection , or it is going bad . or bad ground , also check to make sure that the computer is grounded good

My mechanic in our town did a quick computer check. Car computer indicated a low level of antifreeze, he topped it up, cleared all messages off the car computer and said to watch the the heat guage for any further irregularities. I'll keep an eye on it, love the car, great mileage fun to drive.

1st check the #4 fuse (10A) and #10 fuse (7.5A) on the 'under-dash' fuse block.
then #9 fuse (10A) on the 'engine bay' fuse block.

if the fuses are good, the gauge assembly has has "self-diagnostic" feature.

Self-diagnostic Procedure

The gauge assembly has a self-diagnosis function.
. The beeper drive circuit check
. The indicator drive circuit check
. The LCD segments check
. The gauges drive circuit check (speedometer, tachometer, fuel gauge, coolant temperature gauge)
. The communication line check (the coolant temperature signal line between the gauge and ECM/PCM)


Entering the Self-diagnosis Function:
1. Push and hold the trip/reset button.
2. Turn the lighting switch ON.
3. Turn the ignition switch ON (ll).
4. Within 5 sec., turn the lighting switch OFF, then ON and OFF again.
5. Within 5 sec., release the trip/reset button, then push and release the button four times repeatedly.

NOTE:
. While in the self-diagnosis mode, the dash lights brightness controller operates normally.
. While in the self-diagnosis mode, the trip/reset button is used to start the beeper drive circuit test and the gauge drive circuit check.
. lf the vehicle speed exceeds 1.2 mph (2 km/h) or the ignition switch is turned OFF, the self-diagnosis mode ends.

The Beeper Drive Circuit Check:
When entering the self-diagnosis mode, the beeper sounds five times.

The Indicator Drive Circuit Check:
When entering the self-diagnosis mode. the indicators lights (such as: Seat belt indicator light, Door/hatch indicator light, Brake system light. Charging system light, Low fuel indicator light, maintenance required light) blink.

The LCD Segment Check:
When entering the self-diagnosis mode, the odo/trip segment blinks five times.

The Gauge Drive Circuit Check:
When entering the self-diagnosis mode, the speedometer, the tachometer, the fuel gauge, and the coolant
temperature gauge needles go from the minimum position to maximum position, then return to the minimum position.
NOTE:
After the beeper stops sounding and the gauge needles return to the minimum position, pushing the trip/reset button, starts the beeper drive circuit check {one beep), and the gauge drive circuit check again.
The check cannot be started until the gauge needles return to the minimum position.

The Communication Line Gheck:
In the seif-diagnosis mode, after the odo/trip LCD segments check, the self-diagnosis starts the communication line check.
lf all segments comes on, the communication line is OK.
lf the word" Error" is indicated, there is a malfunction in the communication line between the gauge assembly, the multiplex control unit, and the ECM/PCM,

Ending the Self-diagnosis Function:
Turn the ignition switch OFF.

Note: lf the vehicle speed exceeds 1 .2 mph (2 km/h), the self-diagnosis function ends.
-----------------------

If everything works correctly during the check, check your VSS (vehicle speed sensor)