Jump to content


Photo

Constant Battery Drain - Injection Related ?


  • Please log in to reply
4 replies to this topic

#1 clan-line

clan-line

    Learner Driver

  • Noobies
  • PipPip
  • 18 posts
  • Local Club: none

Posted 04 November 2007 - 07:05 PM

Hi !
I have returned to Mini ownership after 28 years ! My first was a 1960 850 which turned into a 1275 over a period of 7 years.Long gone alas !
I now have a Sprite Auto 1995 SPI acquired off Ebay.And I am very pleased to be behind a mini wheel again.
But....I have a problem.
There is a constant drain on the battery of about 1.75 amps.Battery flat in 2 days.I have spent a long time looking at this fault.
If you disconnect the battery after running the engine and switching off the injection relay module above the servo clicks.Re connect the battery and the consumption falls to around .75 amps.Switch on the ignition and off again and the consumption is back to 1.75 amps.
I have tried a new (secondhand) relay module but no change.If you disconnect the stepper motor connection consumption falls to about 1.1 amps.
I have tried disconnecting most other relays and a number of other connections but no result.
From the Haynes manual I see there is a manifold heater buried away.I havnt tried disconnecting that yet.
Has anyone come across this before ? Any help gratefully received.
Car is mobile as I have fitted a battery cut out switch !
Cheers Iain

#2 clan-line

clan-line

    Learner Driver

  • Noobies
  • PipPip
  • 18 posts
  • Local Club: none

Posted 10 November 2007 - 08:53 PM

An update !
I have opened up the relay module (the one with the 4 relays).
It appears that it is the main relay that is causing the problems.
When the battery is re-connected and the ignition switched on the main relay closes and the fuel pump relay switches for 10 secs and switches off.
But when the ignition is switched off the main relay does not open.It remains on presumably draining the battery.
To get the main relay to open three operations seem to work.
Either disconnect the battery.
Or remove the small plug.
Or remove the large plug.
Looking at the wiring diagram i thought the small plug controlled the relay but was surprised that the large plug had the same effect.
I have tried disconnecting most other relays/sensors but no effect on the main relay.
Is this pointing towards a fault with the ECU ?
Anyone any thoughts ?
Cheers Iain

#3 Sprocket

Sprocket

    Great on Injection faults

  • Members
  • PipPipPipPipPipPipPipPipPipPip
  • 7,266 posts
  • Location: Warrington
  • Local Club: Manchester Minis

Posted 10 November 2007 - 09:04 PM

Two possabilities

First, there may be a short to ground on the main relay wire, that the one that connects the relay pack to the coil, cant remember the colour of the wire but if you look at the pinned topics at the top of the injection section you will find an explanation of the relay pack there, all wires are decribed there.

Secondly, the driver chip in the ECU is faulty giving a permanent ground to the main relay. unfortunately its a new/ re manufactured ECU.


Just make sure the ground connection is in tip top condition, thats the one behind the ECU on the bulkhead cross member, there should be only the ECU ground conneter there. Give it a good clean with emmery paper.

Oh one other slim possability is a fault ignition switch not switvching off the ignition??

#4 clan-line

clan-line

    Learner Driver

  • Noobies
  • PipPip
  • 18 posts
  • Local Club: none

Posted 11 November 2007 - 08:22 PM

Second update !
Firstly thanks Sprocket for the advise.
I have removed the ECU and had a look at the wiring and the earth.
Put a test meter on various bits but could not find any faults/grounding.
I also disconnected the ignition switch but no effect on the relay.
So that leaves the ECU I suppose.It is 12 years old but only done 30k miles.
I dont really want to rush out and buy a new/recon ECU for the Auto as I intend to fit a Cooper manual engine and box in the near future.
I believe that will need a different ECU.
I will use the battery cut out for the time being. Anyone got a spare ECU ?
Cheers Iain

#5 clan-line

clan-line

    Learner Driver

  • Noobies
  • PipPip
  • 18 posts
  • Local Club: none

Posted 18 December 2007 - 07:10 PM

Third update.
After doing some research on the net it seems that Rover MEMS ECUs do have a habit of failing on the main relay circuit.
I was getting a bit fed up with the battery cut out switch idea so sent the ECU off to Auto Matec in Ivybridge Devon.
They turned the repair round in one day.They charged just under £130 all in.
I thought that was pretty good service (I have no connection with them !).
They confirmed the relay circuit fault and found that the idle circuit was faulty.It did idle rather fast before repair.
The car now starts first time after sitting in the drive for a week.
Thanks for the forums assistance !
Iain




1 user(s) are reading this topic

0 members, 1 guests, 0 anonymous users