MR2 Owners Club

Hi. I’m looking for advice please.
I have Mk2 rev5 N/A and it Started and drove it’s usual self on Friday. The car is almost a daily driver. Coincidence that the speedo never worked for the 1st half mile which hasn’t happened before, but that might be a red herring to my problem.
On Monday my car was completely dead, no dash immobiliser, no dash lights, nothing at all. Like there was no battery at all. It started easy with Jump leads and I took it a drive. Came back home and it started no probs when I turned it over again. I charged the battery and after 5 hours my charger was still not showing fully charged. The car locked etc that night.
I bought a new battery today from Halfords, new for old, thinking the battery is goosed. I fitted the new battery, Lunch time today, Car started immediately and battery indicator on the dash was great. Locked it up and went back to work.
I’ve came out tonight and my car is completely dead again. No alarm, no lights on the dash, no central locking.
I could do with any advice u could give. I was sure it was a Dud battery issue but given it’s doing the same problem I have no idea.
Thanks in advance guys.

sounds like you have a parasitic drain.

you need to charge the battery and then start looking for current drain with multi meter.
start pulling fuses until the drain goes away. this will give you a clue to whats id draining the battery.
remember you have 3 fuse blocks - frunk, engine bay, driver side kick panel

usual suspects
head unit (more so if after market)
alarm system (especially if afer market)
alternator
then you are into chaffed wires in looms.

no expert, but on a 60 amp battery, thats one hell of a drain in a few hours

First of all use a multi meter to determine if the alternator is working properly or not. You want 14.7 Volts all the time even at idle or its goosed.

No alternator your battery will be flat in under an hour of driving.

That is really helpful. Got the breakdown guy out this morning, he said the alternator is good, The battery is 14.7 volts. He said parasitic drain as well.
That’s a good process of elimination for removing fuses to see if I can notice the drain.
I jump started it tonight.
I’ll let u guys know what it is when I get to the bottom of it.

Like Jeff said above its pretty hard to get a parasitic current drain that high.

Basically you would expect a fuse to blow at those levels so perhaps you have some aftermarket wiring in there without a fuse or an overrated fuse being used.

Takes a huge current draw to kill a new and fully charged battery in a few hours.

You simply put the multimeter on amps between the positive of the battery and its connector and start pulling some fuses starting with circuits that always have power even when the car is off like the EFI fuse.

By the way with everything off and even an aftermarket Mongoose car alarm, my current draw is only 35mA or 0.035 Amps so this is "Normal".

Yours should be huge if you have a fault, pull one fuse at a time and check the meter, no change put the fuse back in and pull the next one. Repeat until the fault clears. I would first suspect any aftermarket wiring however.

Thanks again guys. Spent a few hours on it today. The drain is consistent between 6-7Amps on my meter. I pulled 1 fuse at a time and the drain continued. With the Battery removed my Ohm meter detected the drain still.
2 things to note.
1. There is a sharp 90 degree bend On my positive terminal which doesn’t look right.
2. My alarm is Genuine Toyota but has been filled retrospectively by the looks of it as the paperwork has been glued into the owners Manual.
I think there is an aftermarket device connected to my Positive terminal which is unfused by the look of it.
Strangely a new issue presented today tho. When I connected my new battery, fully charged, drove the car and the volt meter on my dash climbed up to approx 16volt and all dash lights came on when I accelerated. I know my alternator works but I wonder if the regulator isn’t working. Is this a 2nd issue or is there a chance it’s related?
Regardless, I think I’m going to have to give in and hand it in to the Auto electrician. I’ve exhausted my electrical ability.

6-7 amps is massive, for such a short discharge time it makes sense but are you sure that's correct? Parasitic drain above 150mA is pretty bad, this sounds like you've got a very serious short. Honestly I would disconnect the battery and not use the car until this is sorted, surprised you haven't fried something.

Is the 90 degree the wire bent through 90 or just bolted onto the clamp that way for ease of access? (iv'e done it in the past with some odd batteries for ease of access)

Initially I would trace the main live from your battery to see if any of that's damaged and touching bodywork or other wires, do the same with any wires coming from the alternator. Then trace that bad wiring from whatever a/m device is fitted and either fix it or remove completely.

Stevie2502 wrote: ↑04/07/20 22:15 With the Battery removed my Ohm meter detected the drain still.

How are you testing to come to that conclusion

Strangely a new issue presented today tho. When I connected my new battery, fully charged, drove the car and the volt meter on my dash climbed up to approx 16volt and all dash lights came on when I accelerated. I know my alternator works but I wonder if the regulator isn’t working. Is this a 2nd issue or is there a chance it’s related?

Sounds to me like an alternator problem, voltage regulator is built into the alternator. If pulling all the fuses didn't remove the drain then it could well be a shorted diode in the alternator causing it. Try pulling the plug out of the alternator and also disconnect the main lead from the alternator (disconnect the battery before removing this lead and insulate so it can't short to the chassis/metalwork) then reconnect battery and check again.

If the bend at the positive terminal looks like this then its normal

jimi wrote: ↑05/07/20 2:37

Stevie2502 wrote: ↑04/07/20 22:15 With the Battery removed my Ohm meter detected the drain still.

How are you testing to come to that conclusion

with no battery connected how can you have a drain ?

I maybe haven’t explained it right because auto electrics are not my strength. Father in law was electrical engineer for a chemical plant. Doesn’t know about cars but does know testing. Set my meter to ohms and placed the electrodes of the meter (struggling to remember where I placed them as so many variables now). Anyway because the meter went into a negative reading apparently indicated that it was drawing power.
It’s academic now because I have found the source of the drain. On top of the Positive terminal there is an additional 2 wires which has connected in addition. It joins the rest of the wires in the main conduit. I removed this and no more battery drain. My car is dead tho which i presume must be linked to my alarm and immobiliser as that’s why I get nothing. I took a pic as best I could.

The reason you have no drain (and no power to the car) is that you have disconnected the supply, those two leads are meant to be there and supply all the car electrics. The heavy lead goes to the starter solenoid and starter .. no where else.
As for your testing, you can't get negative ohms, resistance ranges from 0 (dead short) to infinity (open circuit)

Just to provide an answer to my Amp drain. It was my Alternator after all. That’s it all sorted and back on the road. Good as new. Thanks for all the advice guys.

jimi wrote: ↑05/07/20 2:37 05/07/20
Sounds to me like an alternator problem,

Glad it's sorted