[vanasp]

Hi All

I hope someone can help. I was in Southern Mozambique (Ponta Malongane) last week and parked my 3.2 LWB nose down on a steep downhill. After about 2-hours I started the car and the oil pressure light (RED) came on and I thought OK it will go out when I am back on the level road. Unfortunately it did not but as I was only about 1km from my campsite I decided to drive back slowly hoping it would go out.

The next morning I started the car and the light went out, so I thought problem solved. I drove the car for a short distance and the oil pressure light came back on.

Not having a workshop manual with me I traced wiring and found what I assume to be the oil pressure sensor on the RHS of the engine just above the low oil level sensor . Very difficult to get to it (maybe someone can confirm I have the correct sensor). I checked the sensor with my multimeter and it was a dead short. I started the motor and immediately it went open circuit, which I assumed to indicate it was working correctly. I did this check a few times after running the motor and same result every time.

I also checked the oil level and it was fine. I changed the oil 2000km ago and no oil light issues and none on the trip to Mozambique. I could find no signs of any oil leaks and no smoke from the car. The car is also running fine and has full power. I then decided that it was probably an electrical issue and made the decision to drive the 15km of sand road towing my trailer back to South Africa but watched the temperature gauge very carefully. Once on the tar road I hope the light would go out at higher speed but no such luck. The difference now was it was flicking on and off and sometimes glowing faintly.

In desperation I decided to add 500ml of oil in Manguzi (Kosi Bay) to see if it would make a difference. The oil light went off for a short while and then after 5km was back to flicking on and off. This continued all the way to Ermelo but was less frequent by this stage. Suddenly after Ermelo it went off and never came back on again all the way back to Johannesburg.

The oil light is now back on when I start the car but I have not had a chance to re-check the switch.

1.0 Any suggestions as to what could be the problem. (Remember no oil leaks and sensor working).
2.0 Have I found the correct sensor as the workshop manual shows a sensor possibly closer to the oil filter
3.0 Why would the oil pressure light flicker and glow if the sensor is only an open or closed switch (my logic says short in the wiring). The light should then be on or off only. I tried to check the wiring but the section I could see appears to be in order but disappears into a wiring loom.

I really hope that someone can help.

[CATS]

I think the problem is the oil level sensor. My gen3 had that problem. It works almost like a toilet cistern float. In mine the plastic float part broke in two with age I assume and this led to it getting stuck sideways every now and again leading to the oil light going on. I THINK it was the red one but can really not be certain.

I will try and search for my post on it if you like.

Fix was easy. I did it myself after I bought a new part from the dealers. Part was a bit expensive for what it was but within reason for a funny non service item if I recall corectly.

CATS

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[4ePikanini]

oil level light is orange
oil pressure light is red

If it is the red one, replace the sensor and have the prssure checked with a mechanical gauge and compare to factory required spec at x-rpm

[vanasp]

Hi 4ePikanini

As I mentioned if you test the sensor it is working and that is the confusing part.

I am looking for information to confirm if my testing method is correct. Engine off switch is a short circuit and with engine running it is an open circuit.

Cats I think you are referring to the orange light which is the oil level sensor and this is below the oil pressure sensor.

[vanasp]

Ok I have fixed the problem after much searching and crawling under my car. Thank goodness Pajero's are such well built cars it made my problem solving a lot easier.

I disconnected the wire off the oil pressure sender, started the car and the light stayed on my dashboard. This indiacted a wiring fault. I connected a temporary lead (wire) to the oil pressure sensor which is hidden right up high on the engine block RHS (see pictures).

This confirmed that the pressure switch was working when I started the engine. It is short circuit (closed) when the engine is off and goes open circuit (turns off red oil light) when the engine is running and pressure is correct.

I then had to work out where the oil pressure sensor light comes out and on which plug on the dashboard display as I could not find a wiring diagram. It is pin 10 on plug A (see picture). Pin 12 is the hand brake. Easy to test use a multimeter and connect one lead to car body work - negative (I used the big steel bar visible when instrument cluster is removed) and then to terminal 12, turn the ignition on and it will give you a short with the hand break ON. Release the hand break and it should go open circuit (light off).

With the connector still removed from the oil pressure sender I took a tempory lead from connector that would normally be connected to the oil pressure sender and with the car turned off (and on) tried to find it's other end on connector A. Unfortunately I got a reading on terminal 10 and 8. I put some insulation tape over terminal 10 (plug in dash), re-installed the dash and the light was still coming on but it was dim. This showed I still had an electrical fault (short circuit)

I then started to trace wires from the sender unit which then go into a plastic cover (sprag tubing which can be seen in the oil level sensor pictures) from right front then under the car, just about under the front seats and then up the LHS of the car to just under the fuse boxes. I then knew where to look for the fault. I had fitted a dual battery system a few years ago and remembered that the wiring loom was very close to the second battery box. I removed the second battery and could see how all the off road driving has caused it to rub throught the wiring. Luckily only oil pressure sensor wire was effected causing a short to earth. I fixed the damaged wire (tiny hole in the wire) and added extra insulation, some plastic tubing and re-routed the wiring harness to prevent a repeat.

This is wiring harness below where the second battery is installed. LHS side of the car in front of the firewall.

Hopefully this will help someone in the future.

By the way here are some pictures of the oil level sensor which is easy to see and get to with the bash plates removed. It is basically below the oil filter. Look at the first picture and you can see the oil level sensor below the oil filter.

[4ePikanini]

Nice find. Thanks for sharing in detail. Good job!

[mikem]

Thank you for sharing and the nice photo's

[vanasp]

Glad you appreciated it and hopefully it will help someone else in the future. Thanks for taking the time to reply and the recognition.