Battery sensor wire routing?

[Johnricketts]

My ECS light is on, and VCDS displays error 01598 - drive battery voltage -27-00 spurious signal.

 

The fault returns immediately after clearing. The battery is quite new and fully charged.

 

I suspect the thin black sensor wire from the battery negative is open-circuit somewhere. There are no additional errors with this disconnected. I remade the connection at the battery end. Does anyone know where this wire goes so I can track it out? It disappears into a complicated trunking underneath the battery box…..

[Breezy_Pete]

You've posted in the mk1 Fabia section, is that deliberate? If so, what year is the Fabia, please?

 

[Johnricketts]

Yes, It is a Fabia Mk1 2002 1.4mpi, in comfort trim

[Breezy_Pete]

That wire ends up at pin 8 of the connector marked XS4 on the onboard supply control unit under the dashboard, above accelerator pedal.

Worth also checking a fuse in the battery fuseholder that may be relevant, it is one of the blade fuses to the right of the strip fuses (hiding under a black plastic cover), fuse number 10 (5 amp), this has a wire that ends up at pin 5 of the same connector of that control unit.

 

[Breezy_Pete]

If you could get test meter probes up the wire entries of the relevant pins with it in-situ, and measure battery voltage, it would suggest both wires are intact.

If you don't see batt voltage, try again with a different earth point for the meter, to test whether that skinny earth is at fault.

 

This is the connector at the onboard supply control unit, but it's physically mounted with wires downward, unlike in the image. As we look at it here, pin 1 is top left, descending in columns of 3, so pin 5 is second column middle row, pin 8 third column middle.

 

Edited 25 November, 2022 by Breezy_Pete

[Johnricketts]

Brilliant info….am on it. Fuse 10 was fine…..this is my module….trying to find a long wire to ring it through…..

[Johnricketts]

Ok, I just rang it through….see pics. As suspected, it is o/c……. where might it be likely to break?

 

 

[Breezy_Pete]

It looks like you're one column out in where the probe is, to me? Try the one to the right of the one that photo shows the probe in.

[Johnricketts]

Sorry, my mistake. Yes, it rings though fine to pin 8…..

[Breezy_Pete]

See if 5 to 8 measures batt volts (with battery fully connected).

 

[Johnricketts]

Hmmm….battery connected, ignition on, plug still pulled out pins 5 to 8 no volts….

[Breezy_Pete]

You did reconnect the thin black wire to battery neg first?

If so, pull that blade fuse #10 on the battery fuseholder and buzz that wire out to pin 5?

 

No need for ignition to be on, all the battery fuses convey permanent supplies.

 

Edited 25 November, 2022 by Breezy_Pete

[Johnricketts]

ok, I disconnected battery and rang fuse 10 to pin 5….its o/c!

[Johnricketts]

Would you be able to share the relevant wiring diag?

 

Will have to pick up tomorrow, goind dark and just got rained on!

[Breezy_Pete]

Just to confirm, fuse 10 on the battery fuseholder, not in the cabin?

That wire goes through the firewall behind the wiper motor, bottom left (12 way) connector of the left group (as viewed from engine bay), pin 6. Connector labelled P.

Seems much more likely the wire is damaged in the engine bay than the cabin, but worth a look while you've got trim off to see if there's anything obvious near the XS4 connector.

 

 

 

[Johnricketts]

Thanks for your help so far. I think I will have to pull the scuttle panel off tomorrow and check at the firewall. Not been in there before so on a 20 year old motor who knows what may be lurking…..

[Breezy_Pete]

Good opportunity to give it all a clean out.

Go gently with the trim at the bottom of the windscreen (and getting the wiper arms off come to that, do you have a puller?).

That trim comes off upward, perpendicular to the glass, pic:

[Johnricketts]

Thanks for the tips….I have a few different pullers so should be able to adapt something to suit!

[Breezy_Pete]

Could also be worth having a good look locally, near battery, to see if there are any areas of wiring abrasion/damage, before getting to the scuttle.

Best of luck tomorrow.

[Johnricketts]

Thanks. Already checked under bonnet, everything very clean!

[Johnricketts]

Ok am into scuttle now, and removed wiper motor. How does to cover come off the firewall? Do not want to wreck it……BTW, scuttle area full of wet rotting leaves…..blew out with airline!

[Breezy_Pete]

There are clips holding each of those lids on, or do you mean the metal panel between scuttle and engine?

I'll try to find a pic or two of a lid.

 

[Breezy_Pete]

Not sure if these pics help, took them while in there so they could well be lid features. Wasn't recent so memory is vague.

Once the lid is off, each whole connector block is held in by one central T30 torx screw.

[Johnricketts]

Hmm….signs of damp and gunk in there…..

[Johnricketts]

Ok, Batt +ve is not reaching pin 6, but is available on pin 3?

tempted to link it……