SOLVED! Temp Gauge failure - (cluster working - temp sensor also working :))

[Mawrick 0]

I'v had this problem since I bought the car, and realy never looked into it to much, but want to get it sorted - so if anyone got any idea where I might start feel free to chime in.

 

 

Here is a video with the temp-sensor disconnected (Yellow temp sensor)

 

http://s16.photobucket.com/user/Mawrick/media/13050049_zps2cf9e72f.mp4.html

 

Here is a video of the cluster when the temp sensor have been connected again:

 

http://s16.photobucket.com/user/Mawrick/media/13050050_zps46aa5c11.mp4.html

 

 

It will do the same from a complete cold start (on video oil temp was around 60 C).

 

I'v confirmed the cluster is working (in another car), and also checked with another cluster in the corrado with same result.

 

From the vide it seems like it will add a tiny bit to the temp when the sensor is connected, and also the needle seem to rise a bit faster.

 

 

Anyone ever encounter such a problem ? - or have any clues where to start??????

 

 

The car is a 95 VR6

Edited May 20, 2013 by Mawrick

[Mawrick 0]

Is there any way to know which voltages one should expect at the plug ?

 

I can't see the bentley mentiones anything about this ??...

 

Also if anyone else have been reading the wiring diagram - The track numbers I presume is only some kind of reference numbers to make it easier to read ? - and not actuall points on the car.

 

---------- Post added at 9:47 PM ---------- Previous post was at 9:15 PM ----------

 

Just thought I'd add a small pic I made, maybe someone can confirm I'm on the correct path here (as far as I can read from bentley this is the setup for the yellow temp sensor)?:

 

[Jochen744 10]

Hi, So the temp gauge rises to nearly 85/90 even when cold? and if you try another cluster it does the same thing?

the gauges work by having a voltage from the stabiliser unit within the cluster, which runs through a resistive wire around a bi-metalic strip which moves the needle, the wire that runs to the sensor is a earth, and depending on temperature at the sensor alters the resistance in the earth. From memory the wire from the gauge to sensor is normally yellow/red? I would disconnect the gauge temp sender plug, remove the wire plug from dash, locate the wire in the plug and check for any resistance using a multimeter down the wire, there should be none (open circuit) when all unplugged. if there is a resistance, the wire may be shorting to earth slightly somewhere in the loom between dash and sensor plugs. The track numbers along the bottom of the diagrams are a reference point and not related to car points.

[Mawrick 0]

Yea the cluster works fine in a Passat VR6, and the cluster from the passat (wich works fine in the passat) will do this weired thing in the Corrado as well....:(

[Jochen744 10]

well I have worked for VW/Audi for 23 years as a technician, and this fault from my experience points at a problem between the dash insert plug and the coolant sensor (pin 2) on your diagram. It looks like the wire runs through the relay/fuse box, so there may be a issue here? I would advise you check wire with a multimeter, and check for resistance down the wire when disconnected from sensor. or try running a new wire between dash plug and temp sender.

[Mawrick 0]

well I have worked for VW/Audi for 23 years as a technician, and this fault from my experience points at a problem between the dash insert plug and the coolant sensor (pin 2) on your diagram. It looks like the wire runs through the relay/fuse box, so there may be a issue here? I would advise you check wire with a multimeter, and check for resistance down the wire when disconnected from sensor. or try running a new wire between dash plug and temp sender.

 

Will try to check those things out, thnx for the tips - btw any idea what type of voltage one should measure at the plug harness? (I'm not sure if I remember correctly, but I think I did some testing some years ago and found that my Passat VR6 had around 12V at the plug, but the Corrado only had 6 V at the same pin)......anyway, I'l check out the resistance etc to see :)

 

thnx again

[Mawrick 0]

Measured from the cluster now, and seem to be roughly 2.5-3 Ohms, wouldn't think that should affect it that much ?.....

 

---------- Post added at 1:10 PM ---------- Previous post was at 12:55 PM ----------

 

As far as I know it's the blue/white lead that goes directly to the cluster, after doing a bit more testing I find that this wire also have about 166 ohms when I measure from the yellow harness to the negative battery connector.......I don't think it should be that, but does anyone know what would be an expected ohm value from negative battery to this connector ?.

 

Also any tips on where the he*** it can make this connection ?....:)

[Mawrick 0]

Tried disconnecting the cluster again, then I will not get any connection thru to the negative connector of battery - so I'm starting to suspect that there might be something wrong with the harness that plugs into the cluster ????.......

 

I'v double checked the corrado cluster in the passat today, and when putting ignition on the needle stays at the bottom - so at least it seem to be working fine in the Passat.......(the reason I suspect the harness - something/somhow is happening when I plug in the cluster)....:(

 

Any thoughts ?

[Mawrick 0]

Tried to change over the wiring harness that comes from the cluster to fusebox - but still the same problem....

 

I presume it must have something to do with the connection it makes to ground, but dam*** har to figure this thing out :(

 

More tips on where to look???? - Aso the two ground wires that goes to the connector seem to have good connection to ground.

 

---------- Post added at 3:15 PM ---------- Previous post was at 1:31 PM ----------

 

Anyone able to do a measure on theyr yellow sensor and tell me the resistanse value (ohm) you get from the blue/white cable to battery, and the other wire that goes to fan control module to battery.

 

I get following values on the Corrado:

 

blue/white: 166 Ohm

fan-control module: about 1.6 Kohm

 

Passat VR6:

 

blue/white: 266 ohm

fan-control: about 23 Kohm - so a huge difference between the two cars on this value....:(

[Mawrick 0]

Can anyone tell me what the 3 and 5 indicates in this wiring diagram (snapshot from bentley):

 

[Mawrick 0]

I'l answer my own last Q - The 5 means relay position 5, and pin 3 on that relay :)

 

And FINALY!!!!!!!!!!! The problem seem to be gone - for some unknown reason someone have put a relay number 72 into position 5 - where it's supposed to be a relay number 43 (or non at all?), presume it have had a coil that's made a circuit to ground and feeding the gauge :)

 

Easy fix in the end - but damn......:)

 

(I remember when I got it it had this fuel gauge/temp gauge problem - due to the voltage stabiliser, so guess the former owner must have been trying to fix the problem - maybe that's where the relay came from......:( )

 

If anyone happen to have a picture of a relay/fuse box from a late 95 VR6 feel free to post one :)

 

 

This can be regarded as SOLVED! ;)