Operate T6 front wipers with ignition off

M

mod_man

New Member
Hi there,

Another feature I need to implement is operating the front wipers (even if it is just a single "wipe") with the ignition off. I can't seem to find any schematics on the site which have any detail about the front wiper system.

(I found the rear wiper diagrams and got that all working fine).

Can anyone help with the schematics for this?

Thanks very much,

mod_man.
 
Apologies, this is probably a bit of a dumb question, but where is the "coupling point in engine compartment" that the T10az and T10bi connectors connect to?

Looking at page 3 of "60 Window Wash Wipe System_Final".

Any help would be appreciated.
 
They will be connectors in the ‘e-box’ which is the compartment under the battery, it houses all the primary fuses from the battery
 
Hi all,

Thanks for your help so far with my mission activate the front wipers with the ignition off. I'm pretty sure I've managed to find the wires which control and power the windscreen wiper motor.

I'm attempting to get the motor to work by energising the circuit with 12V direct from my secondary battery (with the ignition off), and am not having much success.

I have the battery properly grounded to the vehicle chassis, and am attempting to apply 12V direct to the green wire (input 2 on the motor, or T10c/1). The wipers move ever so slowly, and my wire ends up getting really hot, and glowing red!

Any advice on how to energise the motor to get it to activate nicely? I have done some snooping so far with a multimeter, here's what I have found:

With the vehicle on, and the wipers moving, I see these voltages on the 3 wires:

1) gn/ge: +7V
2) gn: +12V
3: gn/sw: +3

Any advice would be greatly appreciated.

T6 wiper debug.png
 
First thing.. are you using a multimeter to measure these voltages, or an oscilloscope?
They may not be what they appear to be.
 
Just a voltmeter at this stage. I thought I'd see if anyone on the forum has experience with the front wiper system before pulling the scope out.
 
Hi all,

After charging the vehicle battery (it had gotten quite low), I have managed to work out how to get the wiper motor to go:

Connect 1) gn/ge to 12V - wipers on "fast" or:
Connect 2) gn to 12V - wipers on "slow".

The only problem I've run into now is that the wiper lever isn't making the front wiper motor turn. The front washer still goes, which makes me think there's nothing wrong with the lever itself.

I have been doing some reading around the forum, and seen some people having trouble with the front wipers after the battery has been disconnected, or the bonnet open. I've tried "resetting the BCM" by shorting the main + and - leads to no avail. Closing the bonnet lid doesn't seem to help either.

Can't seem to find any blown fuses.

Any suggestions for other things to try?

Cheers

mod_man
 
I expect the BCU is powered down so the internal relay is not operating.
 
Have you back fed 12v into the BCM at any point? Via T73a / 71 or 69? You may have killed it :confused:
 
Grim Reaper said:
Have you back fed 12v into the BCM at any point? Via T73a / 71 or 69? You may have killed it :confused:
Click to expand...

I have directly applied 12V onto those circuits. If I have killed it, it didn't die straight away, I've been tinkering away at this for several days before this fault appeared. I've also managed to apply 12V successfully onto the rear wiper circuits without any issue (yet).

Everything else on the vehicle seems to be working fine.

Is what I've gone and done against best practice? Should I have used a diode or something to prevent back-feeding into the BCM?
 
Modern canbus controlled electrics are so clever nowadays, they often don't use constant feeds but instead use pulses, like when we change headlight bulbs to led ones we see flickering lights because the bcm checks between the pulses for lamp out indications, this means the bcm probably has transistor controlled outputs, which may not take kindly to being reverse biased
 
Grim Reaper said:
Modern canbus controlled electrics are so clever nowadays, they often don't use constant feeds but instead use pulses, like when we change headlight bulbs to led ones we see flickering lights because the bcm checks between the pulses for lamp out indications, this means the bcm probably has transistor controlled outputs, which may not take kindly to being reverse biased
Click to expand...
Righto - will make sure I put in blocking diodes for the next mod! Is it a major operation replacing a BCM?
 
You may have just blown the supply fuse for the stalk that then signals the BCU
 
Loz said:
You may have just blown the supply fuse for the stalk that then signals the BCU
Click to expand...

I hope that's the case - the only problem is when I pull the stalk towards me, the washer pump turns on, just not the wipers :(

I also couldn't find any blown fuses - but then again, I might have just missed one...
 
Hi all, after much probing, debugging, etc, I'm pretty sure I've worked out where the fault with my front wipers. It appears the BCM is unable to output 12V on T73a/71 or /69 (fast or slow wipe). I suspect there is an issue with a blown FET or something in the BCM. There is no issue with the stalk or the fuses.

I've opened up the BCM, and have inspected the outputs on T73a/71 and /69. They are definitely relay selected (OMRON G8NB-17SR), and as such I'm doubtful the wipers are controlled by PWM. Also I can energise T73a/71 and 69 with the loom unplugged and get the wipers to move.

How I suspect I damaged the device was by trying to apply 12V to the wipers directly with a battery - which turned out to be flat. It was only slightly activating the wipers, and potentially creating a problem on the BCM. I may have also had a dodgy ground which could have been creating problems.

Anyways, unless someone on the site has a schematic of the BCM circuit board, I'm probably off to the wreckers to get a new BCM.

Moral of the story: Use a proper vehicle tester probe to energise circuits on the T6, rather than my ghetto battery circuit. Probably also don't let electronics engineers without much vehicle experience near your own vehicle! ;)
 
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