Odd electrical drain problem

westone · Nov 25, 2021

sierrafery said:
Just confirm you let the bonnet opened 18 hours and didnt open any door before you measured?

Thank you.
Yes I did the testing of the FLs first. Car not opened or started for 18 hours.The bonnet was open to do the test and before.It does not have a switch on it, just an empty bracket where one would be.

westone · Nov 25, 2021

PopPops said:
Ah, yes, cross purposes here! In the circuit diagram, what you are referring to as F9, is called "Link 9" which only feeds the compressor relay. If you leave F9 (Link 9) in and pull out the compressor relay, number 5, does the current also fall?

PP

Thanks PP.
I pulled out the compressor fusible link ,when i did this drain dropped.It stands out in the fuse box as its fresh.Not faded.Cannot remember the part about leaving in the fusible link and pulling the relay.I will check..I think the answer is yes, but will check as was so cold by then.!

sierrafery · Nov 25, 2021

Ok, one more test then, if you let FL9 removed and start the engine do you get the SLS warning lights on? IIRC this happened to me long time ago and if it's so the diagram is wrong and in this case IMO the timer in the SLABS ECU is gone and you have to replace the ECU to get rid of that drain

westone · Nov 25, 2021

Thank you for this will try that...hope its not the ecu i need to replace.I do have a spare one in my garage if i need to replace it.
I collect spares like a magpie bird I just like to be prepared.
I will report back after the test tomorrow.

PopPops · Nov 26, 2021

sierrafery said:
Ok, one more test then, if you let FL9 removed and start the engine do you get the SLS warning lights on? IIRC this happened to me long time ago and if it's so the diagram is wrong and in this case IMO the timer in the SLABS ECU is gone and you have to replace the ECU to get rid of that drain

@sierrafery I've just checked my notes from when I was tracking down an unwanted current drain last year. A previous owner had "converted" my car from air to coils by removing FL9 (!!!) so it's not there. No SLS warning lights. For 30 minutes after opening a door I measured 0.6mV across F11, about 350mA and the ABS block was "ticking", then zero, no ticking. My unwanted current drain was elsewhere.

Cheers.

westone · Nov 26, 2021

PopPops said:
@sierrafery I've just checked my notes from when I was tracking down an unwanted current drain last year. A previous owner had "converted" my car from air to coils by removing FL9 (!!!) so it's not there. No SLS warning lights. For 30 minutes after opening a door I measured 0.6mV across F11, about 350mA and the ABS block was "ticking", then zero, no ticking. My unwanted current drain was elsewhere.

Cheers.

Thanks for your input PP.may I ask where the drain was please,so i can cover all bases?
Rain stop play here at the moment.

PopPops · Nov 26, 2021

westone said:
Thanks for your input PP.may I ask where the drain was please,so i can cover all bases?
Rain stop play here at the moment.

The drain on mine was caused by water damage to the IDM (passenger compartment fuse box) which I found by measuring the voltage across F13 in the engine bay. This feeds the IDM and the BCU. (I measured across all the fuses). Luckily, the damage was not too far gone and repairable and the voltage across F13 then dropped to so low (~0) it was unmeasurable and the total drain at the battery was back to 16mA.

One of the problems with "water damage" is the current drawn will vary, sometimes wildly, with temperature and humidity which can lead to false diagnoses. Nothing is ever easy is it?

The bad weather hasn't reached us ........ yet!

westone · Nov 28, 2021

Thank you PP...we had snow blizzards yesterday morning and very cold now.

westone · Nov 28, 2021

sierrafery said:
Ok, one more test then, if you let FL9 removed and start the engine do you get the SLS warning lights on? IIRC this happened to me long time ago and if it's so the diagram is wrong and in this case IMO the timer in the SLABS ECU is gone and you have to replace the ECU to get rid of that drain

I checked this with fusible link removed and SLS lights did not come on.

Then an odd thing happened I sat in the cab and raised and lowered the suspension and all seemed good compressor sounded good car went up to correct height and it went back down same.
I left car then for 14 hours and in the morning checked the drain and it had returned to 0.02amps!

I was shocked and am confused as to why this has happened.

Checked battery volts minimal change even in very cold temperatures.
I checked again to day and still no drain.48 hours later~.0.02amps
I wish i could find out why it happened.

I think the fault must be the ecu or the relay as do not know what else would do it from looking at the diagram.I would be grateful and pleased for your advice Fery on what to do?.
I think it will come back as nothing has changed much.I do not use the car off road, never normally raise the suspension.

I can change all the parts in the system if you think it would be a good idea.

I was delayed a bit responding earlier due to bad weather.

sierrafery · Nov 29, 2021

If the drain comes back out of nowhere better replace the ECU cos IMO the timer in it is making tricks

PopPops · Nov 29, 2021

westone said:
I checked this with fusible link removed and SLS lights did not come on.

Then an odd thing happened I sat in the cab and raised and lowered the suspension and all seemed good compressor sounded good car went up to correct height and it went back down same.
I left car then for 14 hours and in the morning checked the drain and it had returned to 0.02amps!

I was shocked and am confused as to why this has happened.

Checked battery volts minimal change even in very cold temperatures.
I checked again to day and still no drain.48 hours later~.0.02amps
I wish i could find out why it happened.

I think the fault must be the ecu or the relay as do not know what else would do it from looking at the diagram.I would be grateful and pleased for your advice Fery on what to do?.
I think it will come back as nothing has changed much.I do not use the car off road, never normally raise the suspension.

I can change all the parts in the system if you think it would be a good idea.

I was delayed a bit responding earlier due to bad weather.

Fingers crossed it was a once in 100 years software glitch!!

Not the weather for being under the bonnet of the Disco.

westone · Nov 29, 2021

Thank you Fery and PP.
I will wait for the weather to change and then replace it. 1degree C outside now and minus 6 last night.
I have been trying him out today and seems stable.
I will update you if anything changes.

I am grateful for your help....just a bit frustrated cannot find something broken to fix !

Odd electrical drain problem

westone

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