The Mad Hat Man

The Mad Hat Man

Well-Known Member
LZIR Despatch Agent
Anyone got a circuit diagram for a Disco1 300TDi window ECU & wiring. Passenger window wont move down. I don't think its the window ecu as i think that only effects rear windows, so any help appreciated. I have checked switch and door. Everything is connected as it should be. Volts on door connector when switch is pressed "up", but not when pressed "down". Swapped switch - no difference.
My understanding was switch just reverses polarity of wires, so I am at a bit of a loss as to why power to motor is ok when when motor trying to go up, but not down, unless the switch doesn't control the motor directly?????
I have Rave and the 300tdi supplement. Also the paper manuals and they don't seem to cover the "ECU'd" version
 
Have you tried direct feeding the motor in case it's just a duff wire ?
 
Dippypud said:
Have you tried direct feeding the motor in case it's just a duff wire ?
Click to expand...


motor only uses 2 wires, so if there is volts and ground in one direction, it proves wires are ok. my understanding was the the switch reverses polarity, but it seems not unless the ECU is between the switch and the motor - or in the supply to the switch?????
 
The Mad Hat Man said:
motor only uses 2 wires, so if there is volts and ground in one direction, it proves wires are ok. my understanding was the the switch reverses polarity, but it seems not unless the ECU is between the switch and the motor - or in the supply to the switch?????
Click to expand...

Stick a light bulb on it .....

Can you hear it 'clicking' ? the ECU I mean ... I seem to think they should ...

I can only find a D2 diag, (the BCU), from 2003, that has two wires to the switch as well....
 
The rear windows don't use relays or the BCU, they're switched directly by the window switches, which are double pole changeover switches -

or so I'm told now :(
 
Have you got the ECU out yet ?

Have you opened it ?

Does it look like this ?



ecuboardtop.jpg
 
Right !!!

Found this;

You can test for failure of the ECU in rear window power issues, before removing it, by testing for power on the input and output pins of the rear window circuits.

Once you’ve located the windows ECU, note that there are two connectors. The connector with 10 pins is C287, it is used for control signals.
The connector with 8 pins is C288. C288 has heavier gauge wires and is used to deliver power to the window circuits.

1. Input power for the rear window circuits is received on pin 8 of C288 (purple wire next to the white wire).
If you don’t see 12V on pin 8, check the rear power window fuse (F2 of Satellite Fuse Box 2).

2, Pin 3 of C287 (green wire) is a control signal indicating that the ignition switch is on.
You should see 12V on this pin when the ignition switch is on.

3. Output power for the rear windows is delivered on pin 4 of C288 (white wire).
When pin 8 of C288 and pin 3 of C287 are both at 12V, you should see 12V on pin 4 of C288.

If you are not seeing 12V on pin 4, then you probably have a failure in the ECU on the solder joint highlighted in the article.

If pin 4 of C288 is producing a 12V output, the problem is probably in the wiring or switches, not the ECU.
 
There is a diagram in the Haynes manual which looks okay I'll have a look at it tomorrow that will tell me how the windows function, also I may be able to scan the page and attach to post if u don't have a Haynes.
 
discool said:
There is a diagram in the Haynes manual which looks okay I'll have a look at it tomorrow that will tell me how the windows function, also I may be able to scan the page and attach to post if u don't have a Haynes.
Click to expand...


My Haynes only shows 5 pin switches, but my car has 6 pins. so I couldnt use that - deffo wired differently too.
 
Are you sure it's an electrical fault? All the probs I've had with my and RRC and current Disco windows have all been mechanical. Scissor mechanism, motor drive on the big coggy like bit etc. Pull the door cards off and make sure everything is running freely and the glass is not jamming
 
The Mad Hat Man said:
yes - and 3 out of 4 windows work fine.... and the 4th will come up, just not down. which makes me think its something to do with the polarity switching on that window.
Click to expand...

Try the 'good' motor in the window, it'll tell you if it's wiring/ECU or motor ....
 
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