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Oil Pressure Maxed

rcpd34

rcpd34

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Is this problem typically a bad gauge or sending unit?

Thanks!
 
Disconnect the sending unit does it drop to zero? Or is it just stuck? It's not 100% fool proof but that's where I would start
 
stay that way when the trucks off??:dunno: And is it the electric one or mechanical gauge?
 
It's an '89 so it must be electric. Turn key on and it goes to just under 30. Start truck and it moved to max; 60. Turn key off and it stays there until key cycled again.
 
sounds like the gauge to me. my electric one is effed, it goes all over the place. My mechanical one stays at a constant
 
I hope to be getting a parts truck next week; hopefully the gauge in that one is ok.
 
Deuling said:
sounds like the gauge to me. my electric one is effed, it goes all over the place. My mechanical one stays at a constant
Click to expand...
why does everyone a$$ume its always the gauge ?

the sender does all the hard work in HOT and COLD and under PRESSURE all the time for years and also the wire that goes to it also gets tons of heat and gets brittle and breaks off.

a new sender is cheep at under 20 bucks at most and easy to install.

see if the wire is pluged in even.

check to see if you got sender above the oil filter boss on driver side of motor. if so thats for the dash gauge . if not then you have the one on the back of the engine and just behind the intake. ( info for 87-up with tbi engines )

next swap in a new one and make sure to hold the adaptor in block when you try and turn out /in the sender or you can and prob will break it off. :doah: ( did this 1 time :whistle: )

then if this fixes it your good to go. if not then possible wire to dash or gauge. but most the time just the hard working over worked and forgoten sender.

i have changed lots of them on gm and jeeps and the pin hole area for pressure to read is pluged up solid with sludge and or leaking oil from body as its ruptured inside.

did one on my first truck and got 10 psi more on the gauge as old was leaking and reading wrong.
 
I've had a half dozen factory gauges go wonky on me, and zero senders so far...
 
80% of the time it is the sender due to the above abuse conditions and shoddy replacement senders, but gauges do make up for that abuse a bit with their delicate nature..


stupid simple test... disconnect the wire to the sender, key off, gauge should be at 0... with the key on, grd the wire end, it should peg the gauge.. if it does, it's the sender...
 
General Motors 0-90 Ohm Gauge Diagnosis Procedure​
Especially as cars age, it is often somewhat difficult to pinpoint the root cause of instrument cluster gauge failure, thanks to questionable wiring, normal wear and tear, and sometimes even incorrect diagnosis procedures. The following diagnosis procedure is the method that GM publishes in it's shop manuals, will work on oil pressure, temperature, and fuel gauges, and should apply to all but the most recent GM-made vehicles with computerized gauges.
Before You Begin
You will need either Kent-Moore tool J-24538-A, if available, or tool JG-GM-1, a homemade GM gauge testing jumper. To build tool JG-GM-1, you will need the following materials:
  • 1 Jumper wire with alligator clips (about $2 US from Wal-Mart)
  • 1 220 ohm, 1/2W resistor (Radio Shack #271-1109, pack of 5, $0.99)
  • 1 150 ohm, 1/2W resistor (Radio Shack #271-1111, pack of 5, $0.99)
  • about 1" of 1/4" heat-shrink tubing, or vinyl electrical tape
Construct the jumper as follows:
  1. Cut the jumper wire in half, and strip about 1/8" of the insulation off of the cut end of each wire. Tin the bare wires using a soldering iron.
  2. Take both resistors and twist their leads together on each end, so that the resistors are joined in parallel. Twist the leads tightly, cut off the excess, and tin the twisted leads. If using heat-shrink tubing, make sure that the resistor assembly is about half the length of the tubing, or less.
  3. If using heat-shrink tubing, slip the tubing over one of the jumper wire halves.
  4. Solder each half of the jumper wire onto the opposite ends of the resistor assembly.
  5. If using heat-shrink tubing, slide the tubing over the resistors and solder joints and shrink using a low-temperature flame or hair dryer. If using electrical tape, tightly wrap the tape around the resistors and solder joints, ensuring that the solder joints are completely covered.
Diagnosis Procedure
  1. Disconnect wire from sending unit, and connect tool JG-GM-1 from the wire connector to ground.
  2. Turn ignition ON.
  3. If the gauge being tested reads at the high end of the scale (i.e. full for gas, 60psi for oil, etc.), the sending unit is at fault and must be replaced. Retest after sending unit replacement.
    Else, go to step 4.
  4. If the gauge responds, but not accurately, go to step 5.
    If the gauge does not respond at all, go to step 7.
  5. Disconnect engine harness connector at firewall bulkhead. Connect tool JG-GM-1 from ground to bulkhead connector lead that goes to gauge. If the gauge now responds accurately, check the wiring between the sending unit connector and the engine harness connector, repair any faults, and retest.
    Else, reconnect the engine harness connector, and go to step 6.
  6. Remove the gauge from the instrument cluster and check the speed nuts holding the ceramic shunt across two terminals on the back. If they are loose, tighten them and retest gauge; if tight, the gauge is at fault and must be repaired or replaced.
    NOTE:You might be able to repair the gauge with a kit from     Fix-A-Gauge, and/or you might be able to manually reposition the needle where applicable. Retest after repair.
  7. Remove the instrument cluster and check for bad connections at the gauge terminal clips, instrument cluster connector, and both the instrument cluster and sending unit ground. If the connections are good, inspect the wiring from instrument panel to firewall harness connector, and repair any faults if found; if bad, repair the connections, reinstall gauge, and retest. If the connections and wiring are both good, the gauge is at fault and must be replaced.
    NOTE:A gauge diagnosed as bad through this step most likely can not be repaired.
 
ryoken said:
80% of the time it is the sender due to the above abuse conditions and shoddy replacement senders, but gauges do make up for that abuse a bit with their delicate nature..


stupid simple test... disconnect the wire to the sender, key off, gauge should be at 0... with the key on, grd the wire end, it should peg the gauge.. if it does, it's the sender...
Click to expand...


Well at least I have a starting point. Gonna try and diagnose it next week.

Thanks to all who posted.
 
On mine it was the lower sending unit. My K5 has two, one on top and one just above the filter mount down low.

Thanks,
Joe
 
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