Nissan March - Rear demister problem

kenod18

Hey,
Having an issue with the rear demister in my '99 March.
I've checked the fusebox next to steering wheel and they all look ok. The light on the demister switch comes on.
I've checked the voltage with a multimeter at the connection point on the rear window and am getting a reading of 0.
Does anyone know where else I should check?
Thanks!

punisher5112

kenod18 wrote: »

Hey,
Having an issue with the rear demister in my '99 March.
I've checked the fusebox next to steering wheel and they all look ok. The light on the demister switch comes on.
I've checked the voltage with a multimeter at the connection point on the rear window and am getting a reading of 0.
Does anyone know where else I should check?
Thanks!

Check cable on boot lid.

Could be split.

kenod18

punisher5112 wrote: »

Check cable on boot lid.

Could be split.

Thanks, I didn't notice anything when I had quick look yesterday. I'll have a good look later and see. Cheers.

CJhaughey

Check the actual fuses by touching the positive lead of the multimeter to the little prongs that stick out of the top of the fuses, while grounding the negative lead to a ground like a bolt in the door hinge or similar.
The demister should be numbered on the fusebox.
Sometimes you may have to pull and reseat the fuse to get it to function if there is corrosion on it.

kenod18

CJhaughey wrote: »

Check the actual fuses by touching the positive lead of the multimeter to the little prongs that stick out of the top of the fuses, while grounding the negative lead to a ground like a bolt in the door hinge or similar.
The demister should be numbered on the fusebox.
Sometimes you may have to pull and reseat the fuse to get it to function if there is corrosion on it.

I checked the fuses at the box with the multimeter and am getting 12v so thats good.
I pulled the rubber grommet out at the boot hinge and checked the cables. They're all taped up and look fine, don't see any sign of deterioration or cracking.

CJhaughey

Follow the cable back from the window heat strip to the grommet, use a pin to pierce the wire and check for power along the wire, where it flexes is probably where the wire is broken so check before and after that point to see if there is power at any point, also check the grounding for the heater element.

kenod18

CJhaughey wrote: »

Follow the cable back from the window heat strip to the grommet, use a pin to pierce the wire and check for power along the wire, where it flexes is probably where the wire is broken so check before and after that point to see if there is power at any point, also check the grounding for the heater element.

I had a better look earlier, the cable connected to the window goes through the body and in behind the registration plate. This can be gotten to by taking off a panel on the inside of the boot door. Ill pierce the cable here and see am i getting anything. The cables from the reg lights, wiper, and window brake light all meet here as well before disappearing back into the body and i'm guessing up through the grommet on the hinge.

kenod18

kenod18 wrote: »

I had a better look earlier, the cable connected to the window goes through the body and in behind the registration plate. This can be gotten to by taking off a panel on the inside of the boot door. Ill pierce the cable here and see am i getting anything. The cables from the reg lights, wiper, and window brake light all meet here as well before disappearing back into the body and i'm guessing up through the grommet on the hinge.

OK, did a bit more investigating.
In the boot, behind the rear right hand side brake lights, there are a few connectors.
Using the Haynes manual i got the right colour (blue/red) coded wires and found the connector for the demister.
Tested the voltage and I am getting 12v going in and coming out of the connector.
The wire then goes into the body work and up to the grommet at the hinge door.
I've also found where it comes out into another connector behind the panel on the boot door.

I tested the connector in the boot door and got nothing. i then tested the wire just after the bend in the grommet and got nothing.

So there's a break somewhere between the connector in the boot and the bend in the grommet.

Is my best bet to strip the tape off the wire before the bend at the grommet and do some tests there?

Is there an easy way of getting the tape off or is a blade the way to go.

CJhaughey

I'd save some time, pull the grommet out and check there if its good there then cut some new wires and solder and heatshrink a section into the wires and cut the old bad bit out. Then join the new section to the old connectors at the window if they are still in good enough shape.
Sharp blade and carefully cut the old tape is the easiest.
Make sure you use multicore wire so it can flex in the area it needs to.

kenod18

CJhaughey wrote: »

I'd save some time, pull the grommet out and check there if its good there then cut some new wires and solder and heatshrink a section into the wires and cut the old bad bit out. Then join the new section to the old connectors at the window if they are still in good enough shape.
Sharp blade and carefully cut the old tape is the easiest.
Make sure you use multicore wire so it can flex in the area it needs to.

Thanks, ill do bit more testing and see can i find where the connections broke. Hopefully its at the bend

kenod18

kenod18 wrote: »

Thanks, ill do bit more testing and see can i find where the connections broke. Hopefully its at the bend

Decided I'm just going to bypass it completely.
Going to rewire the connector in the boot and run a new wire up to the connector on the boot door, along the same path as the current wires.
Hopefully it works out.

CJhaughey

kenod18 wrote: »

Decided I'm just going to bypass it completely.
Going to rewire the connector in the boot and run a new wire up to the connector on the boot door, along the same path as the current wires.
Hopefully it works out.

That's exactly what I would do.