Fix For Constant Dead Batteries

Getting flat batteries after ~ about 5 days without a drive?

So, you have an alarm installed?

Do your power windows work all the time?

Is your car built pre '95?

NB: This fix is not the only cause of flat batteries. Quite often it may be a faulty door switch or boot switch keeping a courtesy light operating. This fix deals with the door module fix/modification only.

If that's the case, your car is probably suffering the symptoms caused by improper alarm wiring.

The cause of the flat batteries is excessive idle current through the door power relay.

A fairly crude test (making sure the ignition has not been on in the last 20 minutes), is to pull

up the carpet in the driver kick-panel. Place your hand on the big black relay closest to the

floor. Is it warm? If it is, then you have found your problem.

Another good test is to measure with an ammeter, the idle current drawn.

Make sure all doors are closed and no lights are on. Disconnect the battery, and use

a multimeter(ammeter) in series from the positive terminal to the cable that normally connects to

the positive terminal. Leave it connected for a few minutes, as the stacker takes time to go back

to idle after being connected. After a few minutes, have a look at the reading.

Mine was up to 360mA (0.36 amps), way too high.

THEORY:

The Soarers have a pretty sophisticated door control module, designed to control all functions of

the door (windows/mirrors/locks etc.).

When an alarm is installed, it relies on this module to fire the lock solenoids, wind up windows

etc...

Now when the ignition is switched off, the door module is told to turn itself off, until the door

is opened for the first time after the ignition is off. It will then keep itself powered until the door

is closed, or until the ignition is switched back on.

This is where the problem lies. When the door module is not powered, the alarm can not trigger

the locks or windows.

Pretty useless.

What a lot of alarm installers do when installing the alarm, is to wire the switched Ignition

the input of the module directly to un-switched (constant) 12V.

This keeps the module powered all the time and allows the alarm to fulfill its purpose.

But it is not without its side-effects. Keeping the door module powered all the time causes the

door power relay to be driven constantly. This is where the current is going that is causing the

flat batteries.

REPAIRING:

Ok, so we have diagnosed the improper wiring, now it's time to fix it.

The only parts we need are:

 - A 1N4004 diode (available from Jaycar only in packs of 4, part number ZR1004 - $0.40).

 - Either heat-shrink (preferred) or good-quality electrical tape.

 - Small flat-blade screwdriver.

 - Soldering iron, and a small amount of soldering lead.

 - Side-cutters.

 - Preferably a multimeter with an ohms range.

I guess we should start by disconnecting the positive terminal of the battery. Not a necessity,

but always good practice when working with any kind of live terminals, to prevent accidental

shorts and damaging components.

Remove the driver's side lower dash assembly (3 screws, twist footwell light and diagnostic port

about 90 degrees to remove).

Slide yourself on your back, under the dash, and look up. Just to the left of the steering

column, you will see a blue box and a black box with an orange plug. The black box is the door

module we want to remove.

Use the small flat-blade screwdriver to push the tab in on the orange connector and pull

downwards. You might need a bit of force, just make sure the locking tab is pushed in hard, or

else you might do damage to the connecter.

Once the connector is removed, remove the plastic end cap from the black box. There will be a

clip on either side (see attached picture) that needs to be levered for it to slide off.

It's a little bit tricky getting one side off, just have a bit of patience, and try not to bend

it's too far.

 

When that is done, use the flat blade to lever the orange socket that the connector was plugged

into, downwards. This should release the circuit board and slide downwards and out. Just make

sure not to get the electrolytic capacitor on the right-hand side caught on any cabling, as it

may break the legs.

 

 

Okay, so we have the module out.

Warm the soldering iron up and grab the diode. The diode must be placed across pins 6 and 11,

with the cathode (the side with the line around it) side connected to pin 11 (the PINs are

visible on the inside of the connector on the board).

If you see the attached picture, it is much easier to solder the diode flat on the board to the

specified pins rather than soldering it free-air across the pins on the top side.

It may pay to triple-check with the multimeter which pins on the board are pins 6 and 11,

 

otherwise, just use the picture for reference...just don't screw it up!

 

 

Ok, now that you have completed the modification, reassemble the unit in reverse order.

 

Before you plug the door module connector back in, let's fix the improper wiring.

There will be a red wire/black trace next to a large blue wire/white trace on one end. The

red/black wire will be connected to constant 12V - it should be switched ignition. Chances are,

it has just been cut, and connected to the large blue/white wire next to it(see picture).

All you need to do is reconnect the red/black wire to itself again and make sure it is insulated

correctly using either a heatshrink or electrical tape.

 

Done!

 

Re-test the idle current. It should be substantially less.

Re-connect the battery positive terminal.

Just give the windows a quick test. They should only work with the ignition ON, or when the door

is opened the first time after the ignition is off.

 

Congratulations, you now have a correctly functioning door control module and no more flat batteries.

 

 

 

Article written by Jason Kingsmill.

Thanks go to Mark Paddick for the mod details.

CONTRIBUTORS

  - Peter (Soarer Central)

  - @Skinnyboyash