Twisties

Yes, another thread. I've searched and read and am still somewhat puzzled.

I've got a new to me 1997 Sport, 4.0L. The PO had installed a mechanical oil pressure gauge (great), but removed the sender and I suppose to get rid of the "check gauges" light removed the bulb from the dash cluster. For me, monitoring the gauges is no problem, but for my wife and kids I'm a little worried about them keeping up with it.

So I decided to buy a T fitting and run both, and replaced the bulb in the dash, flushed the old (male side) of the connector with contact cleaner, and put in a new sensor. For the first day with my new sensor the electrical gauge is bouncing all over the place, occasionally working correctly, mechanical one is steady as a rock. Check gauge light off when working, on when it's not. Second day and the electrical gauge sits at zero, (but above where the needle is with the ignition off) light on constantly. Thinking it might be a bad sender, I got another one today and swapped it in, same result, sitting at zero, light on constantly.

I'm not worried about driving it because the mechanical gauge says everything is fine, but would like for the light to work as it should. Any suggestions? Try a third sender (from reading here they sound like they flake a lot)? Any thing else to check?

steelybill

There is a gray connector near the alternator on some years, that has the wire for the oil press sender, going to the dash gauge. You might trace the wire from the sender to find the connector, and inspect it for being plugged together OK, or if it needs cleaning etc.
And also the wiring on the gauge itself can be checked for security...
.
Removing the connector from the sender should make the gauge go to high, and grounding the wire in the connector should make the gauge go to low. (with engine off, ign on ) If it reads OK, wiggle the wiring & see if it acts up..

Twisties

Good ideas I'll check those tomorrow. I forgot to mention that when I run the gauge test (trip depressed, turn ignition on, etc), the electrical oil gauge sweeps like normal. That leads me to believe the gauge wiring is OK, right?

CCKen

OP,

Keep in mind that you have an OBD-II Jeep.

There are three wires going to the engine bay sensors, the Oil Pressure Sensor is no exception. One is a 5 volt supply (Orange wire), another is a ground wire to the PCM (Brown/Yellow tracer wire), and the other is the signal wire to the PCM (Gray/Yellow tracer wire). All three must be intact for the system to function.

You'll have to examine the harness connector for the OPS closely for pin cavities being pushed back in the connector, pin cavities being enlarged from Bubba shoving meter probes in them fumbling around trying to troubleshoot the system, corrosion on the pin cavities, and the wires being chafed. You may have to pull the split loom apart far enough back to see the wiring.

Twisties

Wires are wrapped so I'll have to dig into it, but the connector only has two pins? How does that work with three wires?

CCKen

I stand corrected. I just looked it up on the '97 wiring diagrams and it does, in fact, have the two wire system (like the IAT and ECT Sensors). Only thing lacking is the 5 volt power supply (Orange wire).

Do you have a pic of the installation that you could post?

GregGA

Be careful on the "t" fitting you are using. I had a tee fitting holding my oil pressure sender and an Auto Meter low oil pressure sender. After a couple of years the brass fatigued, broke, and pumped out my six quarts of oil. I caught it in time; no damage. Personally, I would use one or the other, which ever proves to be more accurate. Keep it simple.

Twisties

Ok. Ignition on connector on, gauge moves from off up to zero. Same thing with ignition on, connector off.

Definitely two wires on connector, one looks black with yellow stripe, couldn't make out the other.

Here's a pic, connector has red end facing up next to dipstick tube, two holes.

CCKen

Some text from the '97 FSM concerning the OP Gauge:



Diagram showing the Oil Pressure Sensor circuit. Connector C107 is the large connector at the trans dipstick tube. Splice S111 is the splice to the Sensor Ground network. This wire will have around .016-.020 volts on it when the ignition switch is to RUN (engine not running), and zero volts on it when the switch is OFF/LOCK. The Gray/Yellow tracer wire may have around .072 volts on it with the ignition switch to OFF/LOCK, and some higher voltage on it when the switch is to RUN (engine running).

Twisties

Thanks, will get the multimeter out this weekend.

Twisties

Ok, maybe I'm not understanding this correctly. Looks like there's one wire in the diagram going to the sensor, in mine there's very definitely two wires. What looks like a gray/yellow stripe and a dark brown/yellow stripe. Not sure what I need to check on these?

Twisties

Ok, with a little help from someone in the car: With the motor running the gauge flickers on briefly when plugging or unplugging the connector. Could not find a sweet spot to keep it stable. Leads me to believe its something with the connector itself. Have tried cleaning with a pipe cleaner and contact cleaner, no joy. Any ideas?

CCKen

The pin cavities in the connector may be pushed in too far, be enlaged from shoving a meter probe in them or there may be corrosion inside the connector (if you can't see it in the cavities).

Pipe cleaner? What's that? Be careful, some cleaners may hurt plastic.

CCKen

The diagram does show two wires going to the sensor, and with the same colors you describe.

The diagram shows GY/YL = Gray/Yellow stripe, and BR/YL = Brown/Yellow stripe.

The Brown/Yellow stripe wire is the ground network wire.

"Diagram showing the Oil Pressure Sensor circuit. Connector C107 is the large connector at the trans dipstick tube. Splice S111 is the splice to the Sensor Ground network. This wire will have around .016-.020 volts on it when the ignition switch is to RUN (engine not running), and zero volts on it when the switch is OFF/LOCK. The Gray/Yellow tracer wire may have around .072 volts on it with the ignition switch to OFF/LOCK, and some higher voltage on it when the switch is to RUN (engine running)."

Twisties

Thanks for the clarification! Pipe cleaner = fuzzy wire thing for cleaning pipes you smoke. Is there a source for a new connector?