'93 940 temperature guage

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James Sweet - 30 Mar 2004 19:56 GMT

My friend has a '93 940 with a dead temperature guage, the engine has
overheated a couple times now so I figure fixing the guage is the first
order of business. Which sensor controls it? Also is there any particularly
common problem I should look for? Already tried tapping the cluster in case
the needle was stuck, doesn't seem to help.

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Rod Gray - 31 Mar 2004 01:03 GMT

Unplug the connector on the temp sending unit on the drivers side of the
block under the intake. If it is a single wire ground it, then remove the
ground. If it is a two wire connector, short the pins then remove the short.
The guage should swing from full cold to full hot. If not could be the
wiring harness, a connector or maybe a bad connection at the print board on
the instrument cluster.

> My friend has a '93 940 with a dead temperature guage, the engine has
> overheated a couple times now so I figure fixing the guage is the first
> order of business. Which sensor controls it? Also is there any particularly
> common problem I should look for? Already tried tapping the cluster in case
> the needle was stuck, doesn't seem to help.

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Mike F - 31 Mar 2004 14:20 GMT

> Unplug the connector on the temp sending unit on the drivers side of the
> block under the intake. If it is a single wire ground it, then remove the
[quoted text clipped - 10 lines]
> case
> > the needle was stuck, doesn't seem to help.

Actually the sensor is on the cylinder head, right at the bottom,
slightly rearward of the middle on the intake side. It'll have 2 round
pins on the '93.

My brother's '90 740 Turbo had a dead fuel gauge just out of warranty,
and the problem with it was a dead diode inside the gauge itself. This
diode was one that connected the gauge to the power supply, I guess to
protect the gauge if the battery was connected backwards. At the time I
had no diode handy to fix it, so I just shorted the it out, and told him
not to connect his battery backwards! To make a long story short, 10
years later, he still has the car, the gauge still works, and I've not
gone back in and replaced that diode!

Signature

Mike F.
Thornhill (near Toronto), Ont.

NOTE: new address!!
Replace tt with t (twice!) and remove parentheses to email me directly.
(But I check the newsgroup more often than this email address.)

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asdada - 09 May 2004 05:01 GMT

Mike ,

I have a intermittent (mostly off sometimes on) fuel guage on a '94 940.
How would you go about confirming if it the guage or the sensor in the fuel
tank?

TIA

Doug W,
Brampton

> > Unplug the connector on the temp sending unit on the drivers side of the
> > block under the intake. If it is a single wire ground it, then remove the
[quoted text clipped - 23 lines]
> years later, he still has the car, the gauge still works, and I've not
> gone back in and replaced that diode!

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Mike F - 10 May 2004 16:01 GMT

> Mike ,
>
[quoted text clipped - 6 lines]
> Doug W,
> Brampton

I would locate the connector in the trunk that leads to the sender. 2
wires are for the pump (usually pink and black) and 2 are for the
gauge. If the problem is present, connect a resistor across the 2 wires
for the gauge, and see what/if the gauge registers. I'm not sure what
size resistor to use, I think 100 ohms would be a good start. If the
gauge now registers, then the sender is the problem. If not, then
either the wiring from the tank to gauge, or the gauge itself is the
problem. You can check the wires with an ohmmeter, leave your resistor
connected and check the resistance between the 2 wires that are the same
colour up at the cluster with the cluster disconnected and the ignition
off.

Signature

Mike F.
Thornhill (near Toronto), Ont.

NOTE: new address!!
Replace tt with t (twice!) and remove parentheses to email me directly.
(But I check the newsgroup more often than this email address.)

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~^ beancounter ~^ - 31 Mar 2004 03:30 GMT

prob the sending unit on the side of the block...WARNING: this guage
tells you the water temp...not engine temp !! ..so...i am crusin down
the road...and i notice the temp guage spike up...i start headin for
the nearest coolant source...a few miles down the road...the guage
returns to normal...i fig a tem problem w/the coolant...or
something...i fig i have more time to drive...WRONG !! ... once
the coolant drains out of the system...the sensor is exposed to cooler
air...it then reflects the air temp where coolant used to be....screwy
design.....so, try installing the coolant level sensor warning light
(came on later models) that will tell you when the plastic bottle goes
dry in the engine compartment....this is better than a water temp
needle...there should always be 1/2 of the bottle full of
coolant....hope this helps...the 940 is a great sedan....richard /
colorado

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Rod Gray - 01 Apr 2004 01:46 GMT

You are right James. I have seen many engines destroyed because the guage
went to full hot then went back to normal. Once the coolant is gone the temp
sensor only reads the air temp in the engine

.

> prob the sending unit on the side of the block...WARNING: this guage
> tells you the water temp...not engine temp !! ..so...i am crusin down
[quoted text clipped - 16 lines]
> > common problem I should look for? Already tried tapping the cluster in case
> > the needle was stuck, doesn't seem to help.

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James Sweet - 01 Apr 2004 03:21 GMT

> You are right James. I have seen many engines destroyed because the guage
> went to full hot then went back to normal. Once the coolant is gone the temp
> sensor only reads the air temp in the engine

Actually that comment was someone else.

I've heard of that happening though. At any rate the sender was bad, we
ordered a new one, then he'll at least be able to monitor the temperature.

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