Ah ok, cheers.

So, they both run on normal speed when you short the left relay? The right relay isn't used on normal speed, so you could even disconnect that relay and they should still both work on normal speed. This shows that the left relay isn't being energised.

Have you checked all the fuses under the steering wheel? I can't remember which fuse it is, but worth making sure none of them are burnt out.

Also, ceck that you have continuity from pin 2 on the left relay to a pin on the bitron connector. I think it's pin 1, but check them all and if you don't have continuity on any of them then you've got a break in the wire coming out of left relay, pin 2.

If you have continuity from left relay to bitron, and the fuses are all good, then it looks like there's a break between pin 1 of left relay and the fuse.

Working out where the break is, is a tad tricky. First thing is to figure out if the break is in the fan cowling or on the car side. If you undo the fan cowling loom connector, you'll be able to test continuity from the left relay to the pins in the loom connector, fan cowling side. I did this and had to take the fan cowling off the car, but you may be able to do it with the front of the car still attached.

If there is continuity from the relay to the loom connector you know the break is on the car side, not in the cowling.

Yeah I had to take off the bumper, and remove the slam panel so I could lift the fans off. You might be able to do it without doing that, but I couldn't see a way.

That crimping on the bitron connectors could be the issue. You could redo all the crimping if you thought that the job looks a bit crap. Could be a simple fix, but might not be the issue.

I used this as a guide - http://www.306gti6.com/forum/showthread.php?id=135182

Out of interest. What happens when you disconnect the brown sensor on the thermostat? They should come on at half speed. And then both at full speed after a few seconds.

Oh yeh you've got this dash switch. Ideally it would be good to get that completely removed before you start trying to diagnose. Do you know what that is wired into?

Left fan at high speed means that the right relay is fine. On high speed the left fan runs through the right relay on a separate circuit. So it's still pointing to the left relay not being energised for some reason.

Right. ITS FIXED. Firstly the coolant temp sensor wires needed to be replaced with new wires back to the Bitron unit. Also found that the sub loom connector had been taken out and all wires were crimped or soldered instead, however they were all sound. What was found was Pin 1 on the Bitron had no connectivity at the pin but did have connectivity immediately before the wire entered the moulded section which meant the wire inside the sealed part if the connector to the Bitron was where the connection was faulty. Stripped back the resin or what ever it is to get to the wire and got connectivity. Soldered a new wire and sealed it with epoxy resin. The system now runs as designed. How the F*** the wire ever got broken inside the sealed connector bloke is a mystery, but happy days all fixed now. Thanks to all for the info given.

________________________________________

Phil Goodson
405 Mi16 Phase 1 until 2002
306 Gti6 current project car
405 Mi16 LeMans current project car
505 Gti Estate current project car
Audi S4 daily

Cheers, Someone had obviously tried before but failed to find the dodgy connector by the Bitron unit.

________________________________________

Phil Goodson
405 Mi16 Phase 1 until 2002
306 Gti6 current project car
405 Mi16 LeMans current project car
505 Gti Estate current project car
Audi S4 daily