Possible overheating, stuck thermostat?

[stiglet]

Ok cheers Paul. I think what I'll try is to connect each pin individually and see if I can get a normal signal to either the gauge or the Autocheck whilst the car is hot. Tried cleaning up the plug to no avail, so I'm starting to wonder if it's somewhere else in the loom.

Timing really sucks too, as I need the car to move house and then I'll be living out of town.... so i'll need the car to get food and beer It's a complete disaster!

[S2central.net]

Don't sweat it... all those pins from MFTS can be isolated... the only one you need is the T pin for the gauge... I'm insomniac 2nite so will look up wiring here - what the hell

The MFTS is firct on my V6 - temp guage pin - 70 quid odd for a new one. Bahhhhh

[stiglet]

Righto, thanks very much. Back to packing for me. Will give it a go in the morning.

[S2central.net]

7A schematics call up a connector called T7 - a seven pin thing on right side of engine bay (UK driver side)

MFTS Pin 1 = T pin connects to T7 pin 4 on blue/brown
MFTS Pin 2 = R pin connects to T7 pin 5 on blue/white and appears to not connect further (maybe does with aircon)
MFTS Pin 3 = + pin connects to T7 pin 6 on blue/black (12V feed via Fuse 12)
MFTS Pin 4 = C pin connects to T7 pin 7 on blue/yellow (which is in parallel with expansion bottle switch and goes to Autocheck at Pin 10 [ten] on the yellow cluster connector)

Hope that helps - the T7 connector also picks up the wires for oil pressure monitor (on T7 pins 1 and 2) - looks like T7 pin 3 is empty.

[S2central.net]

Oh and that T pin from MFTS on T7/4 (blue/brown) goes to cluster at pin 2 (two) on the yellow plug for the coolant temp gauge

[newsh]

Get a long socket extension or a piece of bar and give the MFTS a sharp tap or two and see if the autocheck warning goes away.

Also check the grounds on the IM.

[stiglet]

Just to update this, I removed the loom from the 7-pin plug to the MFTS (including the oil sender connections) and gave all the pins a good clean up. I've not had the overheat warning since, but then again the weather has been cooler. My temp gauge is still reading incorrect values (i.e. very low) so something is still amiss. Earthed the loom on the MFTS plug for the temp gauge and got a full hot reading, so the loom and plug appear ok, (and the guage is ok too).

So.... I guess it must be the MFTS even though it's only six months old???!?!? I think I'll see if I can get hold of another before I buy one and test it.

Note to self: I hate electronics... still.

[stiglet]

And forget to mention, Newsh I followed your advice and gave it a good bash but alas still no beans Made me feel slightly better though knowing that I had used the hammer

[johne]

If the temperature gauge is reading slighly low, the most likely cause is a faulty thermostat. Remember that the scale on our temperature gauge is deliberately non linear so that it's more sensitive around the 90 degree mark. Jamo posted a good picture of this.

I had to test 4 thermostats to find one that closed at the right temperature (87). Most close low which is why many of us report seeing the gauge reading low when cruising along the motorway.

John

[stiglet]

It's not reading slightly low, it's reading VERY low. Thermostat was replaced when the MFTS was replaced. Plus, I was under the assumption that when a thermostat fails open or opens too soon, the gauge reads low at motorway cruising speeds but normal in traffic. My gauge is reading low ALL THE TIME with very slight incremental changes, as if the signal from the sender has been halved constantly.

Also, this still doesn't explain why I would be getting conflicting signals from the same sender.

I'm almost sure it's the MFTS, when I get around to changing it over i'll know for sure.

[newsh]

And forget to mention, Newsh I followed your advice and gave it a good bash but alas still no beans Made me feel slightly better though knowing that I had used the hammer

Oh well. it was worth a go

[stiglet]

Just to update this, I got hold of a MFTS and this solved the issue. HOWEVER my gauge is now reading temperatures at different positions on the scale. So motorway cruising crusing and "fan on" temps are at slightly different points on the gauge, but at least sensible figures.

Both my old and replacement MFTS's were brand new, both 3 pin and both genuine Mahle. Very odd... but it'll do.

[Acidburn]

cool - did you sort out your wishbone snapping issue?

[stiglet]

HA! Yeah all sorted now. was going to post up about that but never got around to taking pics. When I'm back from Germany i'll post up and see if anybody knows what the cause could be.

[Jas11n]

After having just replaced an original MFTS (my seriously extensive history file makes no mention of one being fitted) with a new one, I too have noticed a slight difference in the gauge reading. The car always sat just a fleas nad over 90, it now sits the same amount below.

Both three pin Meyle sensors.