| Author | Message | ||
| Steve Magnusson (91tr)
Intermediate Member Username: 91tr Post Number: 1030 Registered: 1-2001 |
Can't really add anything more -- the specialized ECUs usually just appear as "black boxes" on the schematics so I don't know how you can get information about what goes on inside. If you've got the dipstick sensor you might measure it's resistance cold and unplugged for comparison. The sensor shouldn't be too unreasonable $-wise (and replacing a thermo-mechanical gizmo after 15~20 years probably shouldn't be unexpected), but from here your guess is as good as mine. | ||
| David P. Tarkington (84mondialcab)
New member Username: 84mondialcab Post Number: 10 Registered: 3-2002 |
Steve, Thanks for the tips. The diagram in the schematic is just like the dipstick oil sensor you provided. The resistance is high across the sensor when cold, so its open. But oddly, shorting across the supply doesn't turn off the light...?! Could the ECU or whatever be smart enough to sense an open vs. a short vs. some small current flow under normal operating circumstances? Then we would have three possible scenarios 1)open sensor fault, very high resistance = warning light on. 2)short fault, very low resistance = warning light on. 3)normal op, small current flow thru sensor = warning light off. The supply line measures 12V. | ||
| Steve Magnusson (91tr)
Intermediate Member Username: 91tr Post Number: 1027 Registered: 1-2001 |
David -- If the sensor on the schematic looks like this Mondial dipstick sensor (from Peter C.):  I think: 1) you could safely try connecting the two wires on the connector together as a test to see if the warning light goes out. The way I interpret the symbol above is that when the sensor is submerged in the oil (and current is flowing in the heating element) enough heat is removed by conduction to the oil that the internal bimetallic switch contacts stay closed (and passing the heating current). If the sensor is not submerged, then the heating current raises the temp of the bimetallic element and the switch contacts open (somehow then turning your warning light "on" -- which smacks of some little horrible "ECU" somewhere). 2) when "cold" and unplugged (even if not submerged) the resistance of the sensor from one terminal to the other should be low (say < a few ohms max) -- if it's open, you'll know the sensor is bad (but that'll be the lucky fix). 3) at least one of the wires coming to the sensor should be +12V (or some other +V) -- if not, the problem is upstream in the power supply stuff. If the sensor on the schematic doesn't look like the figure above -- nevermind... | ||
| David P. Tarkington (84mondialcab)
New member Username: 84mondialcab Post Number: 9 Registered: 3-2002 |
Steve, The light just stays on. There are two wires on the sensor lead. I have a schematic and Ohm Meter. The schematic says they are orange striped white wires leading to connector C3 on the left side of the engine bay and then on to pins 5&6 of the Monitor Check Control (?) not sure where that is yet. | ||
| Steve Magnusson (91tr)
Intermediate Member Username: 91tr Post Number: 1025 Registered: 1-2001 |
David -- If you just leave the sensor unplugged does the warning light go out or stay on? How many wires are attached to it -- 1, 2, more? Do you have an OM with schematic? | ||
| David P. Tarkington (84mondialcab)
New member Username: 84mondialcab Post Number: 8 Registered: 3-2002 |
If I pull that sensor out, can anyone recommend testing tips for it? Or should I just trash it? | ||
| David P. Tarkington (84mondialcab)
New member Username: 84mondialcab Post Number: 7 Registered: 3-2002 |
I'v disconnected and reconnected the sensor several times and started the car in between to "reset" the systems, still the light stays on. The oil level is up. The car shifts fine in all gears now, after I removed a small object that fell in the gate, doh! | ||
| Matthew Lemus (Mlemus)
Junior Member Username: Mlemus Post Number: 56 Registered: 8-2002 |
If you have checked the level and it shifts ok in 4th and 5th and from 4th to 2nd, but the light is still on, Unplug it to reset the sensor and plug it back it. Be sure to spray some contact cleaner on them before you plub it back it. | ||
| Matthew Lemus (Mlemus)
Junior Member Username: Mlemus Post Number: 55 Registered: 8-2002 |
If he is having trouble with 4th and 5th. It is an oil level problem. As for the light coming on, I agree with the car not being level, that would cause the light to come on. | ||
| Steve Magnusson (91tr)
Intermediate Member Username: 91tr Post Number: 1022 Registered: 1-2001 |
David -- If you've verified the gearbox oil level is OK, my guess would be that the sensor has failed. I believe the sensor is a self-heated thermomechanical switch: When submerged in oil, enough heat is drawn out of the sensor that the internal moving (thermomechanical) part stays in the "OK" position. If not submerged in oil, it heats up enough causing the internal moving (thermomechanical) part to move to the "not OK" position. Do you have a schematic? I would hope it's just a simple DC switch/circuit, but if there's an ECU involved then that's another possibile failure area. (Frankly, I'm glad they didn't include this "feature" on my '91.) | ||
| David P. Tarkington (84mondialcab)
New member Username: 84mondialcab Post Number: 6 Registered: 3-2002 |
It has been tough to get it into 4th-5th a couple of times this morning, lower gears no problem. Why would the light have come on in the first place? | ||
| Matthew Lemus (Mlemus)
Junior Member Username: Mlemus Post Number: 51 Registered: 8-2002 |
It could be overfilled. Is it hard to shift. If it is then the transmission is not being allowed to breath. | ||
| David P. Tarkington (84mondialcab)
New member Username: 84mondialcab Post Number: 5 Registered: 3-2002 |
I'm curious about the Trans oil light on in my 84 Mondial Cab. I checked the oil level, might have been a little low, but the car was angled up on stands, so my finger hit the oil when i bent it a little. I added about a half quart regardless. The light stays on. So I added a small amount as well to the side drive gear filler hole. Still, the light stays on. Doesn't appear to be leaking anywhere. Is the sensor sensitive?, could I have fouled its contacts up while cleaning the area with some spray degreaser? Just thought of that... |