Intermittent Issues

Intermittent Issues

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BigJake173

Original Poster:

5 posts

45 months

Sunday 27th June 2021
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I'm looking for some help with issues I've started seeing since I've fitted an instrument console, with a new LCD screen and had an alarm/immobiliser recoded in my T350. I don't know if these are related but I need some advice on how I could diagnose/fix them as they are electrical/electronic in nature and I have little to no experience with these.

The issues are:

1) I am getting an 'Oil Temp Sensor' error which seems to be transient but only when the oil is up to 50c or so - I can clear the error with the steering wheel buttons and most of the time the oil temp displays as expected but occasionally, it has shown 0c for a few mins and then goes back to expected temp.
2) Again a transient 'Fuel sensor' error which clears with the buttons and doesn't seem to show any adverse readings from the fuel tank etc.
3) The A/C temp control switches on the A/C and it works (blowing cold) and the fan regulator works but turning the heat up has no effect. The LED displays the bottom blue lit and nothing else.

I've taken the instrument console back out and checked the connectors are all firmly in place, likewise with the dashboard ECU, alarm and immobiliser connectors.

Could these faults have a common root cause (bad earth or something) or is this how these sensors and controls start to fail? If anybody has any thoughts on how I can start to diagnose the issues I'd be most grateful. I don't mind replacing parts if that fixes the issues but I'd like at least a good chance that replacements will do the trick.

Granturadriver

629 posts

268 months

Sunday 27th June 2021
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All sensor problems can be related to an insufficient ground contact. So you should check all ground contacts.

However, the oil temperature sensor is also a particularly delicate construction. Two cables are soldered inside the sensor and molded in plastic, and the cables have a rubber grommet. The hot temperature in the engine compartment causes the rubber to become brittle and the contacts to break off. I have found this in the spring after the winter break with me and a new sensor was necessary.

BigJake173

Original Poster:

5 posts

45 months

Sunday 27th June 2021
quotequote all
Thanks for that. I'll try and do some rooting about and testing.

zeppo

251 posts

197 months

Monday 28th June 2021
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As mentioned, 1. check/clear all ground connections. I had "wild jumping" oil temp. Readings on my sag and it wasn't the sensor (for the display).

There is a an other oiltemp. Sensor for the ecu, you can display this temp. Reading, when you connect your pc to your car.

Next, check all main fuses, I think there are 3. One under the airbox, one passenger foot area and one some where around the battery.