Fuel relay clicks when brake pressed

[James. 9]

Pretty much as per title. There’s two issues, though I’m unsure as to whether they’re related.

When I press the brake (although it’s the brake light switch triggering it), the fuel pump relay clicks.

I’ve been working on the VR. Testing and changing pumps etc. Installed an ABS pump and bled the brakes/clutch.

When I have a diagnostic cable installed and I switch the ignition to “On”, the ABS light illuminates and goes out as per expected.

When I remove the diagnostic cable, the ABS illuminates briefly and flashes a fault code (1214).

The fuel pump clicks whether the diagnostic cable is installed or not ?

I’ve pulled relay 167 to establish that it is this relay causing the clicks. I’ve also switched it with a known working one and still the same.

I’m very confused (I’ve added a video of both situations).

Anyone had this issue, and have a solution and/or advice?

Thanks in advance for any help 🙂

Edited September 26, 2022 by James.

[Dox 23]

Remove the brake light bulbs and retest

[James. 9]

Removed bulbs and no clicking now !

Next step ?

14 hours ago, Dox said:

Remove the brake light bulbs and retest

 

[Dox 23]

Replace the bulbs with known good ones (not Chinese / Poundland), one at a time. Inspect earth points on rear lights, connectors in the bulb holders, earth on the pedal light switch on the pedal box.

Edited September 27, 2022 by Dox

[fendervg 32]

Has to be a dodgy earth somewhere

[James. 9]

Hmm, back to square one (I think !).

I switched the bulbs out one at a time from the 8v.

Still clicks when the brake is pressed.

Disconnected the pedal switch and the clicking stops.

Caught the rear wiper with my arm. That makes it click. So does:

Headlight switch.

Both interior lights (next to rear view mirror).

Rear heated window switch.

Fog light (when light switch is on) sounds the horn !

 

[Dox 23]

I think ecu supplies an earth to the relay in normal operation (an engine stall cuts power to the fuel pump for safety reasons)?

Those other circuits are also now doing the same?

A poor earth connection, wiring insulation cracked and shorting somewhere, a wrongly connected plug or aftermarket alarm immobiliser?

[James. 9]

52 minutes ago, Dox said:

I think ecu supplies an earth to the relay in normal operation (an engine stall cuts power to the fuel pump for safety reasons)?

Those other circuits are also now doing the same?

A poor earth connection, wiring insulation cracked and shorting somewhere, a wrongly connected plug or aftermarket alarm immobiliser?

It certainly has the “feeling” of a short and/or bad earth.

When I was trying to chase the non start issue, I found the wiring in and around the fuse board was a mess at best (old immobiliser/alarm/tracker wiring). At that point I decided to cut out anything non original and take it back to basics.

Tidied it all up, soldered and wrapped any exposed wiring, making sure colour codes were adhered to.

Because I did all that before it was running, I’m curious wether I’ve connected up something what shouldn’t have, and/or somethings causing a short.

If you have any suggestions as to where to start, I’d be highly appreciative 🙂.

[Dox 23]

I’d start by looking at the earth collection point lower drivers a pillar by the fusebox

[fendervg 32]

Also the earth for the ECU and in the engine bay - these might have been disturbed or damaged when working on the ABS pump. There are earth points both sides of the dash, underneath the parcel shelves near the door frame.

[James. 9]

On 9/27/2022 at 9:07 PM, Dox said:

I’d start by looking at the earth collection point lower drivers a pillar by the fusebox

 

On 9/28/2022 at 10:46 AM, fendervg said:

Also the earth for the ECU and in the engine bay - these might have been disturbed or damaged when working on the ABS pump. There are earth points both sides of the dash, underneath the parcel shelves near the door frame.

Cheers for the guidance.

Double checked the earth points on either side. Checked all the fuses and relays were the right ones and in the right position. Dropped the fuse/ relay panel to check all the wiring colours match up (removed a tracker/old alarm/immobiliser and had to re/join solder parts together) still the same.

Really frustrating as after getting the car running, and the ABS/brakes fixed. Damned electrickery is holding an MOT up ☹️.

I’m trying my best to read (and understand) through bentley, but finding it slow going as it’s like day one of school.

Edited October 8, 2022 by James.

[easypops 8]

Probably of zero help in the actual problem but the fog light and horn wiring is easily mixed up, over by the battery, same plugs. So it’s likely you can eliminate that one 

[1xshaunx1 27]

It could be you’ve introduced 12v to the speed sensor circuit which should have variable voltage. Have you connected a two wire blue plugs together near the fuse box under the dash, these shouldn’t be plugged together or fitted a new stereo 

[fendervg 32]

2 hours ago, 1xshaunx1 said:

It could be you’ve introduced 12v to the speed sensor circuit which should have variable voltage. Have you connected a two wire blue plugs together near the fuse box under the dash, these shouldn’t be plugged together or fitted a new stereo 

Definitely worth checking this one - you can actually use the wire with the stereo provided the unit supports speed dependent volume control (or GALA) - I know for example that the Gamma IV allows this and has a spot in the plug harness for it - otherwise it should insulated and left disconnected.

[Dox 23]

I once owned an Audi 80 cabriolet, every time I pressed the brake pedal the doors would lock via the central lockIn pump, wires to the boot center brake light passed to the boot via the boot hinge, all were broken, cracked insulation and shorting.

did you mention you had a battery drain issue previously ?

[James. 9]

12 hours ago, easypops said:

fog light and horn wiring is easily mixed up,

Funny, we went to the pub yesterday and half way through my first pint, the penny dropped. Couldn’t wait to test the theory in the garage after dinner and yes, I’d got them mixed up 🙄. But yes, many thanks for the heads up.

 

8 hours ago, 1xshaunx1 said:

It could be you’ve introduced 12v to the speed sensor circuit 

Saw the two connectors and left them un-connected. But thanks for the advice.

I’ve spent another couple of hours trying to chase it down this afternoon.

So at this moment in time I have a horn that works. Which means I could conceivably have an MOT test.
 

What I do still have is the remaining fuel pump relay issues.

As of now, when and only when the ignition is in the ON position, the following happens:

The fuel pump relay operates briefly (2/3 seconds) when:

Interior door light is operated

Map reading light is operated.

Make up/vanity light is operated.

Rear window de-mister is operated.

Indicators are operated.

Brake light switch is operated.

When the car is fired up and running, the problems disappear (which tells me it is operating on the lower voltage circuit ?).

I’ve poured over the wiring diagrams of Bentley, in a vain attempt to recognise a link between the above. Spent hours upside down in the footwell looking for clues at the front rear of the fuse box. But have hit a wall 😞

Edited October 9, 2022 by James.

[James. 9]

48 minutes ago, Dox said:

I once owned an Audi 80 cabriolet, every time I pressed the brake pedal the doors would lock via the central lockIn pump, wires to the boot center brake light passed to the boot via the boot hinge, all were broken, cracked insulation and shorting.

did you mention you had a battery drain issue previously ?

I haven’t noticed a battery drain , but I’ll check that next.

Fuse 6 (fans) does blow out every time I turn the ignition on. Not sure if it’s related, but I’m not for ruling anything out at the moment.

Edited October 9, 2022 by James.

[easypops 8]

What about the ignition switch? I changed mine during my very prolonged build but I also had random power issues even after the key was removed. I read on Facebook that there are 2 different types. I’ve swapped from the previous black one back to a cream one but yet to test it. 
Just that you mentioned various symptoms with ignition on 

[James. 9]

O

8 hours ago, easypops said:

What about the ignition switch? I changed mine during my very prolonged build but I also had random power issues even after the key was removed. I read on Facebook that there are 2 different types. I’ve swapped from the previous black one back to a cream one but yet to test it. 
Just that you mentioned various symptoms with ignition on 

That was my next move. My question is that if the clicking goes away when the car is running, would it still be the switch ?

 

[James. 9]

21 hours ago, Dox said:did you mention you had a battery drain issue previously ?

I didn’t, but in typical fashion, I went to the car this afternoon and overnight the battery has run down to 5v (brand new varta battery). To add insult to injury, the power cable from the battery conditioner had snapped and blown the internal fuse (cue spending an hour testing and hunting round for a spare glass fuse). Conditioner now works and is topping the battery up as I type this.

Not even sure what could be draining it. Internal lights were off…

It’s not the only thing feeling drained 😔.

What’s the best way of identifying a drain ? Start pulling fuses ?

[Dox 23]

Don't leave the car unattended with the battery connected until the issue is resolved, have a fire extinguisher with you when fault finding too.

It could be something as simple as a self tapping screw caught on a single wire, most likely behind the dash if its been out?

[James. 9]

Yesterday I had 30 minutes before tea to have another look at the issue.

The battery was literally counting down when hooked up and the multimeter. So I pulled all the fuses out and re-installed them one by one.

All were tickety-boo and not showing a draw. Until I got to the brake switch fuse. Completing the line up and leaving the brake switch fuse vacant showed a stable multimeter reading.

I’m going to have another stab at reading the wiring diagram in Bentley and hopefully locate the issue.

As an aside, the brake lights don’t stay on all the time, which to me would suggest a faulty switch ? And would suggest a wiring issue ??

 

[Dox 23]

Any wiring to the rear clusters shorting to brake light wiring including the hatch fogs n reverse lights - side lights need to be on when fogs illuminate.

 

brake bulbs are live, pedal switch earths the circuit?

[James. 9]

5 hours ago, Dox said:

Any wiring to the rear clusters shorting to brake light wiring including the hatch fogs n reverse lights - side lights need to be on when fogs illuminate.

 

brake bulbs are live, pedal switch earths the circuit?

I’ve had the light clusters out and that all seems good.

Just returned from the garage, where it appears the brake pedal was short of engaging with the switch (probably from when I removed the servo waaaay back).

After half an hour of being folded up in the footwell the battery drain has been cured. It reads 0.09 m/a. Is it safe to assume that number is within spec ?

Fuel pump relay still clicks when ignition is on and brakes/wipers/lights are operated though 🤔