MR2 electrical problems - what's is likely to be?
Discussion
Hi all.
I've returned to the Japanese fold after five years away, with an otherwise-sound Mk2, Rev2 MR2. It's a UK-market GT-i.
However, it's got a few electrical problems. The previous owner told me it had a drain on the battery, and I figured a poke around with a multimeter would sort it out. I've identified the circuit at fault - the one controlled by the 'Dome' fuse, number 1 in the handbook - which includes interior lighting, the warning buzzer, dashboard illumination and the radio. I've checked all these things and none of them remain on when the engine's switched off. The only cause for concern was the courtesy light in the boot, but I disconnected that and the multimeter's still registering a drain.
The other problem I've realised is that the reversing lights aren't coming on. Both of them are out, suggesting it's not a blown bulb. I've checked the gearbox wiring and that's all where it should be. Given that the 'back-up lights' (as Toyota call them) fuse in the engine bay is intact, I'm not sure what else to check.
The annoying thing is that the MoT is due, and without these things sorted it won't pass. Is a cheap fix available or should I just take it straight to the auto-electricians?
I've returned to the Japanese fold after five years away, with an otherwise-sound Mk2, Rev2 MR2. It's a UK-market GT-i.
However, it's got a few electrical problems. The previous owner told me it had a drain on the battery, and I figured a poke around with a multimeter would sort it out. I've identified the circuit at fault - the one controlled by the 'Dome' fuse, number 1 in the handbook - which includes interior lighting, the warning buzzer, dashboard illumination and the radio. I've checked all these things and none of them remain on when the engine's switched off. The only cause for concern was the courtesy light in the boot, but I disconnected that and the multimeter's still registering a drain.
The other problem I've realised is that the reversing lights aren't coming on. Both of them are out, suggesting it's not a blown bulb. I've checked the gearbox wiring and that's all where it should be. Given that the 'back-up lights' (as Toyota call them) fuse in the engine bay is intact, I'm not sure what else to check.
The annoying thing is that the MoT is due, and without these things sorted it won't pass. Is a cheap fix available or should I just take it straight to the auto-electricians?
Reversing lights are not a part of the MOT so don't worry on that, also if you have a drain, make sure battery is decent for the MOT and you're sorted.
With regards to the electrical problem you say your meter is registering a drain on the dome part of the circuit but all these go off when the car is off. However just because they look as though they are off doesn't mean there isn't a fault leading to a draining of the battery. How much is the circuit drawing?
Try isolating the individual circuits within the dome section of the cars electrics. Not easy I know but it's the only way to find the drain.
Also do you have an aftermarket alarm/immob? They seem to like using that side of the cars electrics for powering stuff.
From experience I had a drain and I traced it to the clock on my MR2. Was working as it should, just drew .5amp leading to a flat battery after 4/5 days.
For the reverse lights, check the reverse switch which I think is located on the gearbox
Hope that all helps
With regards to the electrical problem you say your meter is registering a drain on the dome part of the circuit but all these go off when the car is off. However just because they look as though they are off doesn't mean there isn't a fault leading to a draining of the battery. How much is the circuit drawing?
Try isolating the individual circuits within the dome section of the cars electrics. Not easy I know but it's the only way to find the drain.
Also do you have an aftermarket alarm/immob? They seem to like using that side of the cars electrics for powering stuff.
From experience I had a drain and I traced it to the clock on my MR2. Was working as it should, just drew .5amp leading to a flat battery after 4/5 days.
For the reverse lights, check the reverse switch which I think is located on the gearbox
Hope that all helps
Edited by Ug_lee on Wednesday 1st August 11:07
Apparently, the reversing lights are in the MoT, so they do need sorting.
As far as the battery drain goes, I've been disconnecting it whenever the car's left standing for more than an hour, so it's still registering a full charge.
With the multimeter attached, it's registering a 0.71 drain. Remove the Dome fuse and it goes down to 0.01. None of the other fuses register any change so the problem is definitely on that circuit.
As far as alarms and immobilisers go, it's just got the ordinary factory one. The car is completely standard.
As far as the battery drain goes, I've been disconnecting it whenever the car's left standing for more than an hour, so it's still registering a full charge.
With the multimeter attached, it's registering a 0.71 drain. Remove the Dome fuse and it goes down to 0.01. None of the other fuses register any change so the problem is definitely on that circuit.
As far as alarms and immobilisers go, it's just got the ordinary factory one. The car is completely standard.
doogz said:
Given you seem handy with your multimeter, even though both reverse lights are out, I'd still start with the obvious and see if there's 12V going there when it's in reverse.
Given the number of cars I see regularly with both brake lights out, both reverse lights being out, which people are less likely to notice, isn't too unlikely?
Will do, although each rear lamp cluster has its own controlling fuse and all the rear taillights, indicators and foglights work, so it's something controlling the relay rather than the circuit itself - I'm thinking maybe the gearbox switch has broken.Given the number of cars I see regularly with both brake lights out, both reverse lights being out, which people are less likely to notice, isn't too unlikely?
I believe you only need to have one reversing light working for the MoT.
One reason I bought my MR2 was because it was symetrical at the back and had two reversing and two fog lights. I cringe when I see otherwise good looking cars and they penny pinched and ruined the look by only giving one reversing light.
Sorry I vered slightly off topic and can't help with the electrics.
One reason I bought my MR2 was because it was symetrical at the back and had two reversing and two fog lights. I cringe when I see otherwise good looking cars and they penny pinched and ruined the look by only giving one reversing light.
Sorry I vered slightly off topic and can't help with the electrics.
doogz said:
Twincam16 said:
Will do, although each rear lamp cluster has its own controlling fuse and all the rear taillights, indicators and foglights work, so it's something controlling the relay rather than the circuit itself - I'm thinking maybe the gearbox switch has broken.
That's all fair enough, and you do obviously know what you're talking about, but none of that means it's not just 2 knackered bulbs.Just to back that one up I haven't had working reverse lights on any of my MR2's for the last 9 years either. It's a nice thing to have for indicating to others or for seeing a bit of where you are going in the dark. But it will not fail on it.
It'll be a pain, but try pulling the plugs to the various components within the dome circuit while watching the meter, hopefully you'll see the drain go when disconnecting something.
It'll be a pain, but try pulling the plugs to the various components within the dome circuit while watching the meter, hopefully you'll see the drain go when disconnecting something.
What sound system is it fitted with, Passive or Active ?
Some have an amp fitted in the nearside B-pillar, I had a similar problem with battery drain.The amp was drawing power, even after switching ignition off.
I ripped all the amp wiring out and rewired it all for my Sony HU, problem was sorted.
Some have an amp fitted in the nearside B-pillar, I had a similar problem with battery drain.The amp was drawing power, even after switching ignition off.
I ripped all the amp wiring out and rewired it all for my Sony HU, problem was sorted.
MikeyMike said:
Twincam16 said:
Apparently, the reversing lights are in the MoT, so they do need sorting.
Reversing lights are not tested during the MoT. My Rev2 Turbo has no reversing lights, hasn't for at least the 7 years that I've owned it.Edited by Marf on Thursday 2nd August 14:40
Got it sorted now. The drain turned out to be the stereo amp in the B-pillar, but given we couldn't work out what was wrong with it, the electricians fitted a relay so it only comes on with the engine now, and the drain's gone.
Reversing light cable plug had just worked loose. Easily fixed.
Car's perfect now!
Reversing light cable plug had just worked loose. Easily fixed.
Car's perfect now!
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