Circuit connected to 'DOM CUT' relay flattens batteries overnight

[OldBikerPete]

At the moment I'm having a bit of a problem with batteries in my 2013 Diesel LC200. It's got 2 starting batteries connected in parallel and is fitted with a 3rd auxiliary battery connected to the other two by a voltage-sensitive relay. I've just replaced all 3 since the two starting batteries were original equipment and the auxiliary developed a shorted cell. The replacement was triggered by one morning the doors wouldn't open and when I used the key to get in, the start switch only beeped at me and wouldn't even turn on the accessories - lit up the headlights (high beam too) though.

I charged the batteries fully last night and this morning my multimeter showed that the voltage had dropped to 12.57 volts. This would normally start a car no problems except I'm deducing that the computer has a voltage setting below which it will not allow the starting circuit to be engaged - probably a good thing most of the time.

With the help of the auto club battery man, we traced 1.5Amps of current that wouldn't go away to a relay in the fuse/relay box in the engine compartment. The 'map' in the lid of the box identifies this relay as the 'DOM CUT' relay. I have electronic copies of the 2013 users manual and a workshop manual covering models up to 2012. A search in both of these cannot find 'DOM CUT' at all.

Can anyone please point me to an explanation of what this relay controls so I can trace down the leakage?

Thank you.
Peter.

 

[StarCruiser]

Hi Pete, I can only offer generic info as I have no experience of the 200, so forgive me if I’m not much help.

You’ve got quite a few mods to this truck including a tow bar if I read your intro right? Anything connected as aftermarket needs looking at as a matter of course. Often towbar wiring contains a booster relay for the indicators which the fitters often place behind a rear light (on older trucks with standard wiring). That would be where I would be looking first along with anything aftermarket.

In an 80 series, the ‘Dome’ fuse feeds things like interior lights, I think from memory dash lighting, map lights, mirror and glovebox (does anybody put gloves in the glovebox? ) that sort of thing. Maybe your Dome Cut relay disables this so it may be worth pulling it and trying a few things to see if they go dead. Aftermarket sound systems can sometimes cause problems. I doubt you’ve had any water get in but that’s something else to look for as this can often cause this sort of leakage.

Has anything changed or happened just before the problem started?

You could also have a look around inside in the dark to see if there’s a light staying on somewhere. It could be as simple as that.

Your ‘Dome Cut’ maybe a new relay, simply breaker no a feed to some fuse or fuses. Might be worth putting a meter on some of the fuses to see, starting with the ‘Dome’ fuse but of course it may be after the fuse. Just thinking if you follow the circuit in the manual for the ‘Dome’ fuse, it could be the same with just a relay added. Toyota do think quite logically on this.

I’m not sure from your post that you got your truck started after replacing the batteries? There could possibly be some loss of coding for immobilisers that’s happened here. That may be only sorted with a trip to Mr T for reprogramming.

Techstream is available on eBay to read Toyota diagnostics. I know it does the 100 series, it possibly does the 200, but I don’t know. This will probably be worth getting to help diagnose things anyway.

Lastly, i know you’ve already replaced them, but I would be surprised if the OE batteries weren’t still good if given a good charge on a Ctek or similar unless they’ve suffered badly from the over discharge. Many members report 10 years plus from OE batteries. If you’ve still got them, they may be ok.

Good luck with it. Things like this can be tricky.

 

[OldBikerPete]

Hi Pete, I can only offer generic info as I have no experience of the 200, so forgive me if I’m not much help.

Doesn't matter StarCruiser, you tried and you spent a fair amount of time at it. The effort is appreciated.

You’ve got quite a few mods to this truck including a tow bar if I read your intro right? Anything connected as aftermarket needs looking at as a matter of course. Often towbar wiring contains a booster relay for the indicators which the fitters often place behind a rear light (on older trucks with standard wiring). That would be where I would be looking first along with anything aftermarket.

The aftermarket stuff was the first place we looked for the current draw. We disconnected each bit one by one while watching the meter. All the aftermarket stuff tested OK - not drawing any current. I installed it myself so no way it was going the be the source! :-D

In an 80 series, the ‘Dome’ fuse feeds things like interior lights, I think from memory dash lighting, map lights, mirror and glovebox (does anybody put gloves in the glovebox? ) that sort of thing. Maybe your Dome Cut relay disables this so it may be worth pulling it and trying a few things to see if they go dead. Aftermarket sound systems can sometimes cause problems. I doubt you’ve had any water get in but that’s something else to look for as this can often cause this sort of leakage.

Has anything changed or happened just before the problem started?

We did pull the relay - had to do that to confirm that that was the where the current is going. Didn't trace any further as I thought my PDF manuals would help me reduce the possible culprits (I was away from home at the time this problem surfaced). I did notice that the start button became completely inactive with the relay out.

This car gets driven very little and lives in a dry garage and it had done so for a couple of months before having a job done on the rear bumper and fuelling up days before departure on a short trip dragging our caravan Melbourne to Geelong where the problem surfaced. The only thing done to the car was that rear bumper remove-replace job and it lived in its garage for about a week before starting with no trouble to go on the short trip which was completely dry until well after the problem appeared.

You could also have a look around inside in the dark to see if there’s a light staying on somewhere. It could be as simple as that.

Your ‘Dome Cut’ maybe a new relay, simply breaker no a feed to some fuse or fuses. Might be worth putting a meter on some of the fuses to see, starting with the ‘Dome’ fuse but of course it may be after the fuse. Just thinking if you follow the circuit in the manual for the ‘Dome’ fuse, it could be the same with just a relay added. Toyota do think quite logically on this.

Yes, it looks like I'm going to have to spend a bit of time with a meter tracing down the items following that relay, including 'DOME' fuse.

I’m not sure from your post that you got your truck started after replacing the batteries? There could possibly be some loss of coding for immobilisers that’s happened here. That may be only sorted with a trip to Mr T for reprogramming.

Sequence of events.
Problem surfaced, auto club battery man replaced the two starting batteries, went for a 60km drive and the car stood overnight - same problem next day. Battery charger for 5 minutes got it started. Noticed that the auxiliary battery was down 10 10.5Volts. Auto club man tested the aux and detected dead cell, aux replaced and auto club man and I traced the current draw as far as the relay. Charged all batteries fully and car stood overnight. Next morning same problem - starting batteries down to 12.57 volts, overcome by 5 minutes on the battery charger. Drove 100km home and garaged the car and I'm sure that when I go out tomorrow morning, the same fault will be there.

Techstream is available on eBay to read Toyota diagnostics. I know it does the 100 series, it possibly does the 200, but I don’t know. This will probably be worth getting to help diagnose things anyway.

Lastly, i know you’ve already replaced them, but I would be surprised if the OE batteries weren’t still good if given a good charge on a Ctek or similar unless they’ve suffered badly from the over discharge. Many members report 10 years plus from OE batteries. If you’ve still got them, they may be ok.

Good luck with it. Things like this can be tricky.

I have a Scanguage installed which can read fault codes amongst other things - there are none.
We're planning a long trip perhaps starting in May for about 3 months. There's no way I was going to trust 4-year-old batteries on that trip as we'll be back-o-bourke for a lot of it. The batteries only discharged to 12.5-ish volts which is about 50% charge and not so discharged that damage would be done. Mr auto club man took the old batteries away.

Similar problems have been reported on other Toyota sites (Camry) and one of the suggestions was that a leaky alternator rectifier diode might be the culprit. Mr auto club man tested the amount of charging volts and got a good reading but I'm not sure that such a fault would be diagnosed with the meter he was using.

As I said, looks like I'll just have to spend some time with a meter.

Thanks again.
Peter.

 

[IRLGW]

The truth is, it's a diesel ,and diesels don't like aussies. You could try rebadging it with v8 petrol badges and see if the problem goes away.

Have you tried replacing the actual relay? Every time my headlight relay melts it drains the battery but still operates for a while. If its connected to your start stop button then it could be on the ignition wire and following on starcruisers advice this may be were something else has been spliced in. disconnect the alternator overnight and that will eliminate that.

 

[StarCruiser]

Along with disconnecting the alternator overnight which could be a good call, you could have a look and see what the charge voltage is with the Dome Cut relay out. If it drops away you know it’s on that circuit. Yes a bad diode can drain the battery so disconnecting overnight would eliminate that.

 

[StarCruiser]

Purely based on when the problem started, I would say it’s more than worth the effort to have a very good look around that rear bumper. It’s possible a wire has been trapped or something reassembled wrongly. The fact the problem surfaced straight after it was refitted seems a strong suspect to me. It needs ruling out at the very least.

 

[OldBikerPete]

Purely based on when the problem started, I would say it’s more than worth the effort to have a very good look around that rear bumper. It’s possible a wire has been trapped or something reassembled wrongly. The fact the problem surfaced straight after it was refitted seems a strong suspect to me. It needs ruling out at the very least.

The truck's on float charge in the garage at the moment. That'll be one of the first places I'll look. Thank you.

 

[OldBikerPete]

The truth is, it's a diesel ,and diesels don't like aussies. You could try rebadging it with v8 petrol badges and see if the problem goes away.

LOL

Have you tried replacing the actual relay? Every time my headlight relay melts it drains the battery but still operates for a while. If its connected to your start stop button then it could be on the ignition wire and following on starcruisers advice this may be were something else has been spliced in. disconnect the alternator overnight and that will eliminate that.

Hmm. The only thing which fits that bill and which hasn't been cleared is the ARB trailer brake controller. Have to test that. Thank you.

 

[OldBikerPete]

The truth is, it's a diesel ,and diesels don't like aussies. You could try rebadging it with v8 petrol badges and see if the problem goes away.

Have you tried replacing the actual relay? Every time my headlight relay melts it drains the battery but still operates for a while. If its connected to your start stop button then it could be on the ignition wire and following on starcruisers advice this may be were something else has been spliced in. disconnect the alternator overnight and that will eliminate that.

The relay itself had occurred to me, I have test gear at home and will test it when I get a round toit. The truck's on float charge in the meantime.

 

[StarCruiser]

The brake controller woukd go to the rear bumper…to connect the trailer, wouldn’t it?

 

[OldBikerPete]

The brake controller woukd go to the rear bumper…to connect the trailer, wouldn’t it?

Yup!

 

[OldBikerPete]

Hi Pete, I can only offer generic info as I have no experience of the 200, so forgive me if I’m not much help.

You’ve got quite a few mods to this truck including a tow bar if I read your intro right? Anything connected as aftermarket needs looking at as a matter of course. Often towbar wiring contains a booster relay for the indicators which the fitters often place behind a rear light (on older trucks with standard wiring). That would be where I would be looking first along with anything aftermarket.

In an 80 series, the ‘Dome’ fuse feeds things like interior lights, I think from memory dash lighting, map lights, mirror and glovebox (does anybody put gloves in the glovebox? ) that sort of thing. Maybe your Dome Cut relay disables this so it may be worth pulling it and trying a few things to see if they go dead. Aftermarket sound systems can sometimes cause problems. I doubt you’ve had any water get in but that’s something else to look for as this can often cause this sort of leakage.

Has anything changed or happened just before the problem started?

You could also have a look around inside in the dark to see if there’s a light staying on somewhere. It could be as simple as that.

Your ‘Dome Cut’ maybe a new relay, simply breaker no a feed to some fuse or fuses. Might be worth putting a meter on some of the fuses to see, starting with the ‘Dome’ fuse but of course it may be after the fuse. Just thinking if you follow the circuit in the manual for the ‘Dome’ fuse, it could be the same with just a relay added. Toyota do think quite logically on this.

I’m not sure from your post that you got your truck started after replacing the batteries? There could possibly be some loss of coding for immobilisers that’s happened here. That may be only sorted with a trip to Mr T for reprogramming.

Techstream is available on eBay to read Toyota diagnostics. I know it does the 100 series, it possibly does the 200, but I don’t know. This will probably be worth getting to help diagnose things anyway.

Lastly, i know you’ve already replaced them, but I would be surprised if the OE batteries weren’t still good if given a good charge on a Ctek or similar unless they’ve suffered badly from the over discharge. Many members report 10 years plus from OE batteries. If you’ve still got them, they may be ok.

Good luck with it. Things like this can be tricky.

PROBLEM SOLVED. Found that my ScanGuage connected to the ODB connector inside the cabin was drawing 200mA even when it has shut itself off when the ignition off - I'll chase warranty over that issue. AND Replacing the 4-year-old car batteries helped AND replaced the batteries in the electronic keys.

I expected that a car as computerised as the 200 is would produce some sort of warning when the electronic keys need a fresh battery - not so. I also expected that both our electronic keys would not require replacing at exactly the same time - but they did.

 

[StarCruiser]

Well done finding it and thanks for posting up the result. Small batteries like those in remote keys have a finite life and if they’ve had similar use can die at a similar time. To have them both go at exactly the same time is odd but not impossible.

Glad you’ve found it. Hope some of my ramblings were if help to you.

Best
Rich