Seat Motors not functioning (undisgnosed problem)

[danwade333]

Hello everyone!

I made this post in the Facebook group and I got many replies however none were for the problem I had described. I think most had not read my post properly so I will try to describe as best as I can.

Both driver and passenger seats won't move up or down. Forwards or backwards with the side switch.

1. Both motors have been tested and powered directly from the battery and are fully operational.

2. 12v is supplied to the loom under neath the seat so power is not an issue

3. + and - 12v is supplied to directly where the motors are connected to the loom when the seat switched is pushed forward or backwards so the switch is not an issue and is functioning correctly

4. Fuses have been checked and are un broken.

5. Seat bushes replaced and the tracks have been cleaned and lubricated and are free moving when the spindles are driven directly by a hand drill.

But when the motor cables are reconnected to the loom under the seats, they do not move either forwards or backwards and show no signs of life when the switch is pressed.

Even when the drive spindles are disconnected from the seats the motors don't move.

Any one experienced anything like this or have I missed anything obvious?

Thanks alot

 

[Eddie Zedder]

Seems strange that both seats have the same issue. Possibly a dodgy earth connection that's common to both.

 

[NZ00Z3]

Hi

A little bit of information is missing in your post.
- What is the build date of your car?
- Do you have standard or sport seats?

This will allow us to find the right wiring diagram for your car and help you.

You can find the wiring diagrams for the Z3 in the Resources section of this forum. There are 4 sets, depending on the build date of your car.

 

[danwade333]

Hi Guys,

Thanks for the responses

It's a 1998 2.8 with standard seats.

I've since done a bit more fault finding.

I've removed both bases from the seats to make troubleshooting a bit easier.

I've found both seat bases now work correctly when connected to the passenger side loom.

But neither work when connected to the drivers side loom which narrows it down to that as the fault.
It changes what I thought before I couldn't get the passenger side to move either.

I've double checked all fuses both number 5 and 19 on the engine bay fuse box.
Are there any more that are unlisted that anyone knows about?

I recently had all the carpets and trim out due to water in the footwell so I'm wondering if that could be the problem? The fault developed just before I had taken the seats out to inspect and further found the water under the carpets.

Has anyone had experience replacing a wiring segment?

 

[Mario]

I would say you have corrosion or a cable broken on that side. the good news is if you can't find the problem you could wire an extension to the other side that is working and splice it there - technically unless you are moving both seats at the same time you should be fine in terms of amperage etc if you were to do that.

 

[danwade333]

Does anyone know if I use the earth cable, from what I think is the heated seat module on the left, will that potentially solve the grounding issue or are they connected together.

Or simply a new grounded wire to that point.

I'm almost sure its the grounding on the drivers side as some of you have said thankyou!!

I'm getting +/-11.5 v in the passenger seat

and +/- 10.5 v in the drivers seat

Only difference is both seats work on the passenger side and neither work on the drivers side.

I've tried to tell from the electrical wiring diagram but I'm still not 100% sure

Thanks

 

[Momo77]

Did you find the fault? I have exactly the same problem. It would be good to know what went wrong.
Thanks

 

[danwade333]

I'm afraid not. Couldn't narrow it down to anything. There was just a voltage drop or possible earth fault on the driver's side loom.

I just purchased a 12v battery which sits in the rear storage and ran the wires to the seat. Works normally and you can't tell. You just need to charge the battery every few weeks.

 

[danwade333]

.

 

[Momo77]

Mate, I found the fault at mine which is exactly same problem as yours. Very easy fix in the end.
I removed the driver seat this evening and pulled the carpet. I'll post a fix tomorrow.
I was daunted by this problem.