Electrical Gremlins

[Dutch24V 0]

Not sure where to post this but...

 

I've been investigating why the fuse for my blower motor keeps blowing and have found that both my reverse lights aren't working either. Both bulbs and the fuse are ok (I tested the bulbs and fuse elsewhere) but they just don't light up?

 

What side of the car do the wires for the reverse lights run? When we did the heater matrix and the dash was out we tidied up some wiring up that sits down by the blower motor (LHD car rememer so on the right side). I'm wondering if somehow we've shorted a wire from the reverse lights to a wire from the blower motor, but for some reason the fuse or bulbs haven't blown for the reverse lights (and the fuse for the reverse lights is 15 amps, where as the blower motor is 30)???

 

I can't figure it out and there doesn't appear to be anything else wired into the blower motor wiring to cause the fuse to keep blowing, even when the motor itself is diconnected?

 

Any help/ideas greatly appreciated as short from ripping the whole f*cking dash out again I'm stumped.

 

Dutch

[White2505 0]

I had a similar problem with my reverse lights.

 

On top of the gearbox is a black housing held on by two bolts which has a connector coming out of it. This connector goes to a small switch inside the housing.

When I took the housing off there was a mild steel circular cup which was bolted in the centre to the selector mechanism (this presses against the switch and turns the reversing lights on. The bolt had worked loose and thus the mild steel cup was not applying any pressure to the switch within the black housing and so not activating the lights.

10 minutes with a socket set MAY solve your problem.

 

If it's not the circular cup, whilst you have the black housing off the selector mechanism try manual pressing the switch (with it still connected obviously) and se if the reversing lights come on (don't forget you will need to have the ignition switch in the on position)

 

hopefully should be this simple

[White2505 0]

Just reread your post the blowing fuse for the fan motor is likely to be a seperate problem altogether. The reversing light failure is most likely to be a seperate fault acting as a red herring!!

 

Try disconnecting the +ve power lead to the fan motor itself, replace the fuse and try activating the fan switch. If the fuse stays good this suggests the fan motor itself is faulty.

try turning it by hand (has it seized? does it feel REALLY stiff to turn) this suggests the bearings have seized or something similar)

was it squealing prior to the fuse blowing or did it sound like it was struggling to provide any air flow??

 

let me know how you get on.

[Dutch24V 0]

White2505, thanks for the info. regarding the reverse lights. I will have a look at the switch etc. to see if I can find anything odd.

 

With regards to the blower motor, it's all new, including the thermo pack. Also, the fuse still blows if the fan is disconnected.

 

You're right in that it could just be a coincidence that the reverse lights have stopped working at around the same time as the fuse started to blow.

 

The fuse didn't blow straight after I replaced the heater matrix either. It lasted for a week, then started blowing every other day, until now when it blows the instant the ignition is switched on (with the motor disconnected too)

 

Dutch

[White2505 0]

Sounds like a wire got trapped whilst installing the new motor and the insulation has chaffed through over the period of that week until it's reached a point of constantly touching a +ve supply wire to earth hence the immediate and constant fusing.

Sounds to me as though, unfortunately, the motor is going to have to come out to check the wiring behind it.

Sorry :(

[RW1 0]

I think two separate faults as said? Hope this helps…….

 

The 30 amp blower motor (cabin) fuse also powers the 3rd stage cooling fan and the rad. Fan control unit. The feed wire tee’d off between the relay plate and the dash switch. The supply also goes directly to the third stage fan switch in the thermostat housing. It’s not the yellow but the brown thermo switch if fitted. The wire is Black/Yellow. Also the same wire turns up at the rad. fan controller. No other loads on the circuit. So the cabin blower fan being isolated hasn’t taken out all the electrical loads.

 

Reversing light . Loom wires down the left side. First break after the fuse box is a 2 pin in line connector in the left side of boot. If this is separated then rear fog light won’t work either as other pin of the two is used for this. Have you checked the reversing light switch in the engine bay. Black wire is ignition 12 volts. Black/Blue is output to the reversing lights. Switch connection is forward of cables under the rad. Fan.

 

.

[Dutch24V 0]

RW1, Many thanks, I think you're onto something. :)

I didn't know the fan controller runs off fuse 6 too. I wondered why it was a 30 amp fuse for such a little motor!?

 

Anyhow, taken from another thread, my other ongoing issues are related to the cooling system, inparticular the aux pump. after run:

 

"My Aux. pumps bearing is shagged so it makes alot of noise when it's running, but when I turn the ignition off when the engine is hot, the aux. pump stops and the cooling fans run for only 30 seconds or so, then stop for a minute or 2, then restart for 30 seconds again and so on? Any ideas anyone? Relay 14 maybe??"

 

 

Having read your above post I'm fairly sure I have a problem with the fan control unit and/or the third stage fan switch. I had a quick check this morning though and the clearly visible fuses look ok and the cooling system works still with the engine running, but when I turn the ignition off, the aux. pump dies, regardless of engine temp.?

 

Is this Black/Yellow wire that triggers the 3rd fan speed also involved in the aux. pump after run circuit btw?

 

Can you confirm that the aux. pump should run WHENEVER I switch the engine off, hot or cold?

 

Dutch

[Kevin Bacon 5]

Can you confirm that the aux. pump should run WHENEVER I switch the engine off, hot or cold?

 

Yep.

 

Modern VWs that have after run cooling (such as the Polo that was at Stealth a fortnight ago) do exactly the same.

[Dutch24V 0]

Cheers Kev, think we've isolated the problem to one of 2 things then.

It could be a coincidence of course but looks like my fan controller or the 3rd speed switch in the thermostat is shagged and this is what keeps blowing my fuse.

 

...BUT, I remember when we met up a few weekends back you said I did not have the 3rd speed switch, or it was different as the temp. sensor wasn't connected and it had 4 pins instead of 2? Do you remember, you also mentioned at the time that I could run factory fit air co. as I had a 4 pin black temp. sender?

 

 

I'm confused now...

 

Dutch

[Kevin Bacon 5]

Yeah that's true, yours appeared to be minus the black sender!

 

The black sender if present wouldn't blow your 30A fuse anyway as the 2nd and 3rd speeds are ignition level at way less than that sort of current. The fuses for the fans are in the controller and speed 3 uses the huge 50 amp fella. There are no rad fan related fuses inside the car, except fuse 15 which supplies the after run motor.

[Dutch24V 0]

Err, according to RW1:

 

The 30 amp blower motor (cabin) fuse also powers the 3rd stage cooling fan and the rad. Fan control unit. The feed wire tee’d off between the relay plate and the dash switch. The supply also goes directly to the third stage fan switch in the thermostat housing. It’s not the yellow but the brown thermo switch if fitted. The wire is Black/Yellow. Also the same wire turns up at the rad. fan controller. No other loads on the circuit. So the cabin blower fan being isolated hasn’t taken out all the electrical loads.

 

...and:

 

Relay 15? No, not Aux Pump relay on a VR6, the fan controller with temp sensor in the thermostat housing for that on a VR6, the one that drives the coolant gauge in the dash. Plus the ignition key has a trigger to the circuit as Kev says.

 

Now I'm even more confused?

 

Dutch

[Kevin Bacon 5]

So am I mate, so am I......

 

Brown thermoswitch? It's the black 2 pin sensor that triggers speed 3, unless the car has aircon and then there'll be another 4 pin sender and appropriate wiring. Black/yellow is correct though.

 

I got 'Fuse 15' from the VAG owners manual mate and says "After run cooling system (VR6)" but I'd suggest you try and get a copy of the ELSA diagrams yourself if I were you, especially ones related to your own version of the car.

[Dutch24V 0]

Hmmm, maybe RW1 will shed some light on the issue when he's next online?

 

Can somebody PM me details about getting a copy of ELSA then please?

 

Dutch

[Kevin Bacon 5]

The genuine ELSA wiring diagrams might be hard to get hold of. Have you not got the Bentley, which I think RW1 is referencing from?

 

You might have to get your hands dirty mate and just do some good old fashioned end-to-end fault finding.

[Dutch24V 0]

I don't mind doing some fault finding, but I need to know what I should be testing before I can fault find. :?

 

I don't think RW1 is referencing the Bentley on this though as he stated the Bentley wiring for the fan after run etc. is wrong as it only relates to Yank cars (see http://www.the-corrado.net/.archive/forum/viewtopic.php?t=32792)

 

Dutch

[Kevin Bacon 5]

He might have the ELSA diagrams then..... but they're not gospel either as I found out during my OBD2 conversion.

 

Well you said the interior fan motor fuse keeps blowing, so starting there and tracing it's wires back to the fuse board would be a good start and also trace the other circuits that hang off that track as RW1 suggested....

[Dutch24V 0]

Yep, will try and do that over the coming weekend.

 

...but if the fuse also runs the fan control module and 3rd speed fan switch I'm thinking the problem probably lies there as my aux. pump over run doesn't work either - which is controlled by the control module if I understand RW1 correctly?

 

Dutch

[RW1 0]

but the brown thermo switch if fitted

If fitted it's in the third hole on the thermostat housing, if fitted.

 

If no brown 3rd fan switch (this is not the run-on after igniton off etc)(same position is used in the thermostat housing for the factory air-conditioning sensor), then there is only the fan controller loaded on the circuit, tee'd off as written before.

 

ELSA, that's a lioness isn't it?? No, ELSA only covers post 1995 cars in general and the Corrado isn't on it except for the VR6 engine mechanicals & engine ECU.

 

---------

 

As I read it early on in the first posting.

 

even when the motor itself is disconnected?

 

Disconnecting the cabin fan didn't stop the fuse blowing so it's either a wire short or another component.

 

If a short in the supply to the switch, then the fuse will blow no matter which fan speed is selected. If it's a short in the wires from the 4 speed fan control switch to the fan motor connector, then it should only short on one setting of the fan speed. (Also see the notes on the rad.fan controller as the “tee’d” wires are from this section of single wire)

 

After that, it's down the tee'd off wires to the fan controller & third thermo-switch Wire colours earlier are on.

 

Auxiliary pump is powered directly off the fan controller. And the Yellow sender in thermostat housing is its sensor as well as being the dash temp. gauge sender. Disconnecting the auxiliary water pump electrical connector will eliminate the doubt over that item causing it.

 

is wrong as it only relates to Yank cars (see http://www.the-corrado.net/.archive/forum/viewtopic.php?t=32792) [/quote:ffd0b]

 

Ah wrong twist... DelMonty was using those relays on a late car where the relays had no relevance.

 

"Therefore you cannot assume cos the Bentley shows relays, they should be there. The diagram has to be read in conjunction with the relevant year’s wiring diagram to determine whether it exists for a Corrado/engine fit made in that year. Then the Bentley diagram doesn’t apply anyway for the top two rows on European Corrados"

 

The point about the Bentley in the thread is that they can only be used as a guide. Hope that clears that up.

 

"it’s a handcrafted car for a specific set of markets with separate requirements. The Scirocco & Cabriolet are the same. Therefore the Bentley (USA & Canada wiring standards) can only be used as a guide, not a bible."

 

---------

 

Dutch if you have the Bentley, then goto the Corrado SLC 1994 model pages. Should be the same as I described earlier but if you can’t find the third rad. fan speed thermo-switch on your car in the thermostat housing, it isn’t fitted.

 

Chris

[Dutch24V 0]

Hi Chris, thanks for the detailed reply again :notworthy:

 

Let me try and clarify the situation a little:

 

I have just tried the fuse with the motor disconnected AND the switch for the speed selector also disconnected and it still blows instantly.

I have just looked at the thermostat housing and I find, from left to right, 1 dark coloured sensor with a 4 pins connected, the blue sensor with 2 pins connected and the brown sensor which has 4 pins but none are connected.

My aux. water pump and radiator fans all work when the ignition is on (and engine running). When I turn the ignition off though the aux. pump stops, regardless of engine temp. If I turn the ignition on again the aux. pimp starts again. Due to the aux. pump not running when the ignition is off and the engine hot, the rad. fans pulse on and off due to the coolant not moving through the system.

 

From what you've explained so far, I'm tending to think that the fan control unit is the suspect. This would explain why the aux. pump doesn't run when I turn the ignitioin off, and could explain why the fuse inside keeps blowing too.

...BUT, if it is at fault and causing the fuse to blow, how can the rest of the cooling system work properly when the car is running (including the aux. pump circuit)? Is the circuit for the aux. pump different depending on the ignition switch position? If so that would explain it!? :?

 

It could also be that the wire from the fuse box to the fan speed selector inside the car is shorting somwhere, and the fact that my aux. pump doesn't work when the ignition is off is totally unrelated?

 

From the description above is it worth just whacking in a new control unit (at some cost) and hoping? I'm going to trace the wire from the fan speed selector to the fuse box tomorrow too, but don't see that even if I do find a short how this could effect the aux. pump over run circuit?

 

Dutch

[Dutch24V 0]

...I've just had a thought 8)

 

Maybe the aux. pump IS the problem here? I know the bearing is badly shagged as it makes a lot of noise. Maybe the resistance is causing the 20 amp. fuse to blow on the circuit connected to the inside blower fuse, but as it runs on a different circuit when the engine is running it works ok?

...but then the fuse should blow when I turn the ignition off, not on surely?? doh..., I don't know anymore, starting to do my head in now...

 

Dutch

[Supercharged 2]

A knackered motor will draw large amounts of current....

[RW1 0]

“have just looked at the thermostat housing and I find, from left to right, 1 dark coloured sensor with a 4 pins connected, the blue sensor with 2 pins connected and the brown sensor which has 4 pins but none are connected. ”

 

1st two sensors are OK, as expected. 3rd one, Brown sensor is telling me that the car has air-con, yeah? 30amp rather than 20amp in Fuse 6. 20 amp is no air-con and the 3rd sender is Balck with only 2 pins rather than 4. No wires at the brown sensor means where are they??? Third stage fan are Black/Yellow & Black/White wires. The air-con are Green/White & Green wires. I wonder if they are tucked away and touching 12 volts to earth, either the Black/Yellow (most likely) or the Green/White wires would blow the fuse (air-con “norm” or “max” switch has to be switched if this is fitted).

 

I’m guessing but this engine may have worked air-con in the past and when you fitted it, it didn’t get air-con but the brown sensor wasn’t wired up for the 3rd stage fan or a 2 pin Black sensor fitted to be compatible with the car’s connector???? Haven’t got enough history of the car to understand which way the wires should be. Air-con or not air-con on the car side of things????

 

I doubt the Auxiliary Pump is the fault as there is a 5amp fuse protecting it on top of the fan controller. Just disconnect the Fan controller connections and test whether the fuse still pops. Also this fuse 6 supplies the air-con, so knock both switches off to isolate those circuits.

 

Some of the fan controller 12 volts supply comes via fuse 19 30amp via the rad. thermo-switches in the rad. That’s why some of it works.

 

Wire from fan speed controller to relay fuse panel is Black /Yellow and is same colour for tee’d to fan controller. The branching point is behind the relay panel. The relay panel loom plug is Q which is Blue and is a single vertical row connection, 6 pin. From left of car it’s on the top row, ie plugs Black, Black, Black, Green, Blue, Blue, Blue. Q is the middle Blue of the three Blues. Black/Yellow wire goes into pin 2, 2nd wire from the centre line of the panel. Worth tracing as it will eliminate the “trapped wire” in the dash thoughts.

 

Chris

[Dutch24V 0]

Brown sensor is telling me that the car has air-con, yeah?

 

Nope, the car doesn't have air-con, but the engine isn't the original so may well have come from a car with air-con.

 

So there should be at least 2 pins of the brown sensor connected for the 3rd speed? I will check around and see if I can find the missing connector.

 

I'm also going to try and trace the wire behind the dash today so we can eliminate that, and I will disconnect the fan controller to test that too. I've just returned from VW and have 20 30-amp fuses to play with now :)

 

I will report back my findings, thanks again...

 

Dutch

[RW1 0]

So there should be at least 2 pins of the brown sensor connected for the 3rd speed?

 

Yes for 3rd speed. The little loom has all three sensor's wire bundled together so it can't be far away. The positive is a Black / Yellow wire and the earthy side Black/White. I will need to look at pin numbering tonight for the brown sensor.

 

I wouldn't put a 30 amp fuse in as that will possibly cause damage as it take more time to blow, given you have no air-con electrical loads.

 

.

[Dutch24V 0]

Well, I can't find the wires that are missing, at least not in the loom you mention with the other temp. sensor wiring.

 

There is a conector down by the right-hand side head light that has two wires of the same colour you mention though? It looks like it's trapped under the battery so will see where it's run too another day now.

 

I disconnected the wiring to the fan controller (the plastic clip with about 6-8 wires in, not the larger power wires though) and the fuse still blows instantly with a bright flash!?

 

I'm beginning to think a wire is trapped and has gradually worn through and now shorting the circuit somehow. I presume it's in the wiring before the inside fan speed selector as the fuse still blows when the switch is disconected?

 

Looks like I'll have to remove some more bits of dash over the weekend to investigate further :(

 

..also the reverse light switch on the gearbox is still connected, so maybe it's broken as my reverse lights still don't work either?

 

Dutch