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peter hamblin

Mysterious Rav4 Abs Problem...help Please

20 posts in this topic

Hi everyone...I'm new here and am hoping some of you experts may be able to help.

My wifes car, a 2002 RAV4 2.00 VVTi, has a very intermittent strange problem.

In the morning,when the car is started,the ABS and brake warning lights stay on. After warming up,if the car is switched off and then back on again,the ABS and brake warning lights go out.I have tried hard braking to see if the ABS is working....when the light is on...no ABS. When the light is off...ABS is fully functioning.

Here's the strange bit...whenever the light is on..the heater fan won't work,but when the light goes out,the fan starts working again.

Mr Toyota did a diagnostics,and said a fault code for an ABS solenoid shows up..but no fault code number......£750.00 plus fitting plus VAT please. But how can this affect the heater fan????

I am convinced that this is an obscure electrical issue,but cannot put my finger on it.

Can anyone help..please?

Thanks is advance...Peter

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Welcome to the club.

Funnily enough they are both wired through the ignition switch and that problem is almost definitely a poor feed. Don't buy that ABS unit just yet!!!

You could either try wriggling the ignition when it fails or the plugs on the back of the fuse boxes of which there are several. You could try a direct feed from the battery just to prove it. I can provide you wiring info if you will understand it but if not just take it into a sparky.

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Not got wiring diagram for pre 2003 4.2, but having a very quick look post 2003, the ABS motor and solenoid direct battery feed and the blower motor feed all come of 100A fusible link MAIN2 and I haven't found anything else fed off that link (yet!).

Not unreasonable for loss of ABS motor and solenoid supplies to throw a DTC and turn the light on.

That would happen if that link was dodgy and you'd get no blower either.

Now, I'd be the first to admit that it is an odd thing thermally for a fusible link to do and if it is dodgy, you might expect something like, oh, perhaps higher than normal resistance and therefore a large volt drop under high current load (e.g. ABS activation) and therefore more ABS problems and stored faults and/or even the thing blowing completely - but perhaps it is worth a look.

Now you are going to ask where MAIN2 is. I dont' know, probably in one of the under-bonnet fuse boxes.

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Thanks fellas....I would appreciate a wiring diagram...even if I can't fully understand it,I will be taking it to a sparky.

I can't find MAIN 2 on the fuse box diagram..only MAIN which is 30A and appears to be "H-LP RH and H-LP LH" which I assume is headlamps.

I'll try wiggling around the ignition switch.

BTW...how would I try a direct battery feed? I don't know whether this is relevant,but these problems only started after the battery was replaced a couple of weeks ago.

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I'm no sparky but i wonder if disconnecting the battery for an hour or 2 may help ? making sure you have the stereo code if it's coded of course.

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Hi Ravi...I tried that,but only for about 10 mins. The light cleared ,but then came back again the next day.

I have just been to see a local auto electrician...first thing he said was..try the ignition switch,by wiggling it when the light's on...exactly what anchorman has suggested. He said that Citroen have the same thing,caused by the heater fan load gradually causing ignition switch contacts to 'corrode' and if the abs is also on the switch it will cause these symptoms.

As to Mr Toyota..he said.."Well..they just make it up as they go along".

He's going to look at it soon,but, anchorman...if you have that wiring diagram I would hugely appreciate getting a copy...do you want an e-mail address?

Cheers, Peter

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Hi Ravi...I tried that,but only for about 10 mins. The light cleared ,but then came back again the next day.

I have just been to see a local auto electrician...first thing he said was..try the ignition switch,by wiggling it when the light's on...exactly what anchorman has suggested. He said that Citroen have the same thing,caused by the heater fan load gradually causing ignition switch contacts to 'corrode' and if the abs is also on the switch it will cause these symptoms.

As to Mr Toyota..he said.."Well..they just make it up as they go along".

He's going to look at it soon,but, anchorman...if you have that wiring diagram I would hugely appreciate getting a copy...do you want an e-mail address?

Cheers, Peter

No they are less than 2Mb;

abs fuse.pdf

abs wire.pdf

ac wire.pdf

relay loc.pdf

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Hi anchorman....Many,many thanks. I'll let you know the outcome.

Thanks again...Peter

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Urgghhhh!..... Tried wiggling the ignition key...no effect.

BUT...now the thing is intermittently dead when inserting key in ignition...and sometimes the blower fan now works when the ABS light is on.

This has got to be all to do with a U/S ignition switch...hasn't it??????

It's doing my head in now!!!

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It depends what you mean when you say inserting the key. Do you mean when the key is in fully and turning it??? The ABS and the AC are only powered up when the key is in the run position (ignition on).

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Hi anchorman....It's intermittent dead when turning the key to crank the starter motor. Also,since this happened (today) the engine is lumpy on tickover.This has happened before when the battery has been disconnected to reset the ECU.After a a few local runs, the engine ticks over fine.I understood that this is the ECU "re-learning" the correct settings...at least that's what an AA mechanic told me some time ago.Otherwise the thing is running fine..no loss of performance or economy.

Maybe I'm completely wrong...but it seems to be losing all battery power to certain systems???

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OK well it certainly sounds like it. However, that isn't so straight forward so to be sure you can bypass the switch wires or you can take the plunge. You'll need to talk to Kingo and see whether you can buy the switch independant of the lock otherwise you will end up with an odd key and one that needs programming to the ECU. They don't say much in the manuals in case little Johnny scumbag can read but if you can separate the switch from the lock that is the most trouble free way.

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Thanks again...as I'm new here,I don't know who Kingo is. From what little I can find,(you're right Mr T doesn't like people bypassing their extortionate market price rigging,so this info is very difficult to obtain), I believe the barrel and switch can be obtained separately.

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Here's Kingo: LINK :thumbsup:

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(you're right Mr T doesn't like people bypassing their extortionate market price rigging,so this info is very difficult to obtain

It isn't that - its a security measure to stop some little dirtbag learning how to break into your motor.

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Hi anchorman. Sorry for my cynical comment about Toyota....frustration at their apparent policy of replacing high value components without really knowing what the fault is.

I have now found an independent Toyota specialist,who says that you seem to be correct about the power supply. He's having a look at it this afternoon. I'll let you know what he finds.

If he is as good as he sounds (on the phone),I will have no hesitation in telling you all who he is,as he may be able to help others with similar frustrations that I have. I'm in Berkshire,so I guess there are plenty of Toyota owners who could benefit from having a good local specialist.

Rgds,

Peter

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Hi anchorman and others who have helped out with this problem.

Well....it's fixed!!!!! Took it to the specialist this morning,and he went straight to the problem.

There is a connector block adjacent to the + terminal of the battery...underneath it,and out of sight, a connector was loose,and as soon as he touched it,it fell out. Plugged back in and all OK (fingers crossed).

He did a full diagnostics as well,and the bonus is that he's identified the sensor causing the EML to be on.He can fix that for £100.

Cost so far..£20 to sort out the problem and do a full diagnostics.

This guy knows his Toyotas,and I thoroughly recommend him to anyone.

The Company is.....UK Teknics,Taplow, Berkshire. Wally is the genius there.

Thank you so much everybody,and especially anchorman...you're the best.

Best regards,

Peter

btw...is it ok to put a post on here recommending a specialist?

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:thumbsup:

You can post a recommendation but need to be careful posting links that are considered traders. They need to subscribe to sell and apply to be traders.

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Hi,

Having read through I see its now fixed, I'm new to Toyota's and not sure of the systems etc.

Thought I'd reflect on something I've come across before, the exact same sysmptoms on an old XR4x4 Sierra I used to own, in that senario its a sure sign the battery is dying, the ABS is via high pressure electric pump and not Vacuum Servo, the inital self tests, abs pump running and engine cranking, pull the battery down and the ABS fails to initialise, 100 yards down the road, turn off the engine and re-start straight away and the ABS initialises ok.

One of the biggest electrical problems my mechanic mate finds is bad earths, a loose bolt on an earth strap can wreek havoc..

Regards Austin..

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Hi Austin...the battery was replaced just prior to the problem starting...so in light of the cure;it must have been the act of battery replacement that nudged the connector enough to cause electrical problems.

5 days on..and no evidence of the problem returning.

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