Help finding battery drain

[Bowser]

So after leaving my 172 for 3 months over winter, it has developed a parasitic battery drain.

I've narrowed it down to fuse 21 and 29 (when removed, the drain stops)
21 = Multi timer, Diagnostic socket, Central locking, Instrument panel and decoder unit
29 = Consumer cut out, Interior light, radio, clock

I've tried the easy things like unplugging stereo, interior light, boot light.
And it presumably has to be something that runs without the ignition on.

So im not sure where to go next, these 2 fuses cover such a wide array of items.
I imagine its due to being stood for the last 3 months, so a bad earth possibly.

Any suggestions, as i may be missing the obvious..
cheers

**Something i noticed - when placing the multi meter across negative lead and negative terminal, to measure drain, i can hear a relay click under the glove box - only once, whenever the circuit is made.

 

[Bowser]

How do i go about disconnecting, central locking, instrument panel, clock etc?
I know what circuit this fault is on, but not sure how to narrow it down

 

[STEVE.M]

How do i go about disconnecting, central locking, instrument panel, clock etc?
I know what circuit this fault is on, but not sure how to narrow it down

Has it occurred to you that these circuits are live for a reason and all that is required is to replace the battery?

 

[Bowser]

Replacing the battery wont help. I have an excessive drain coming from this circuit.
I think 100 milliamps is acceptable drain, and i have +250Ma.

 

[STEVE.M]

Replacing the battery wont help. I have an excessive drain coming from this circuit.
I think 100 milliamps is acceptable drain, and i have +250Ma.

Even 100 Ma is too high.
Diode pack on back of the alternator naff?
Try disconnecting the alternator.

 

[Bowser]

Alternator doesn't seem to be the cause.
Cleaned engine bay earths up, and will do gearbox earth tomorrow.

Both of those fuses have to be removed to rectify the problem..
21 = Multi timer, Diagnostic socket, Central locking, Instrument panel and decoder unit
29 = Consumer cut out, Interior light, radio, clock

My head hurts. Any more suggestions would be great..

 

[STEVE.M]

Alternator doesn't seem to be the cause.
Cleaned engine bay earths up, and will do gearbox earth tomorrow.

Both of those fuses have to be removed to rectify the problem..
21 = Multi timer, Diagnostic socket, Central locking, Instrument panel and decoder unit
29 = Consumer cut out, Interior light, radio, clock

My head hurts. Any more suggestions would be great..

There is a gearbox loom earth underneath the battery that can suffer corrosion.

You could eliminate engine earthing by lashing up something like this or use a jump lead.

I had a mirror switch cook itself for no apparent reason, which eventually blew fuse 29, but must have been drawing current before hand. Worth disconnecting on the off chance.

 

[JamesBryan]

My recent battery drain was sorted by replacing the alternator, dodgey diodes.

What does the draw go down to when you take the live off the alternator?

 

[STEVE.M]

My recent battery drain was sorted by replacing the alternator, dodgey diodes.

What does the draw go down to when you take the live off the alternator?

I hope this was done this afternoon, as I recommended it 6 hours ago in post 5.

Answers along the lines of " Alternator doesn't seem to be the cause " always puzzle me though?

Either you yanked the wires and it made no difference, or you didn`t bother.

 

[Bowser]

Not sure why its puzzling.. I disconnected the alternator from the equation, and the draw on the battery did not change. Am i missing something then?

 

[Bowser]

Interesting you had a mirror short out, i will try and disconnect mine

I don't understand why basic things like mirrors and clock, are on the same single fuse as instruments and ECU related things. Makes fault finding a PITA.

 

[Bowser]

Ah so the live from the alternator splits off before reaching the battery it seems..
Whats the best way to fully isolate the alternator then? Removing the heavy live from the side of it?
Appreciate the input btw

 

[STEVE.M]

Not sure why its puzzling.. I disconnected the alternator from the equation, and the draw on the battery did not change. Am i missing something then?

If you had written that, I would not have commented.

If you read through to post 36 of this thread, you will understand why people become a little jaded.

https://www.cliosport.net/threads/182-misfire-whats-causing-it.807438/

It`s an injector, No it cant be time & time again until the final admission that it was an injector.

 

[Bowser]

You suggested disconnecting the alternator, so i did.
Maybe i didn't do it correctly. but i didn't ignore your advice.

 

[Bowser]

Sorry, i misunderstood your post. I thought you were saying i was ignoring you..
So, should i be disconnecting alternator from the alternator end, and not just the battery live?

 

[STEVE.M]

Ah so the live from the alternator splits off before reaching the battery it seems..
Whats the best way to fully isolate the alternator then? Removing the heavy live from the side of it?
Appreciate the input btw

It`s the thick 10mm red lead that you need to disconnect.
This can be done safely from the battery end, which will also disconnect the + feed to the starter motor, as they are wired in series.

 

[Bowser]

Ok, well sadly this didn't fix it.
Its something that runs through fuse 29 and 21. So will try and disconnect the mirrors tomorrow.
Do you know if one of the relays under the glove box should click when the battery is connected but ignition off?

 

[STEVE.M]

[QUOTE="Bowser, post: 11563349, member: 105457"
Do you know if one of the relays under the glove box should click when the battery is connected but ignition off?[/QUOTE]

This is why I give up.
Do you mean does a relay click constantly when the battery is connected, or just once when you connect the battery?
If the latter, that will be quite normal.

 

[Bowser]

The latter...
Disconnected wing mirrors and no change.

Other than checking earths, wiring condition and disconnecting alternator - is there any other basics i should be checking, before i resort to pulling the dash to bits and disconnecting things?

Could the constant live that feeds fuses 21 and 29 be at fault?
Id have thought the problem would remain after removing the fuse if that is the case.
Am i right to assume the problem is 'after' the fuse..

Thanks to anyone with suggestions.

 

[Bowser]

So don't know if anyone is actually reading this, but will keep posting as it may help some poor sod in the future.

The only things on fuse 29 i haven't unplugged are the clock and consumer cut.
What is the Consumer cut out?? Cant find anything on google.

 

[STEVE.M]

So don't know if anyone is actually reading this, but will keep posting as it may help some poor sod in the future.

The only things on fuse 29 i haven't unplugged are the clock and consumer cut.
What is the Consumer cut out?? Cant find anything on google.

Did you get to the bottom of this, and your throttle surge problem?
Is the fact that you intend to look at a Cup related?

 

[Bowser]

Yes and no.
The parasitic drain was a poorly chock blocked wire behind the radio, so sorted that.

The surging issue - hopefully..
Despite the injectors having correct resistance and firing when removed, i think one or more is faulty when the car is actually running.
The whole problem got a lot worse recently, so yesterday i unplugged the injectors whilst the car was running and 3 and 4 made almost no difference when unplugged...
Wish id done this a month ago, but i assumed the resistance check and spray test was adequate.

New injectors on order..