57 Yaris 1.4 D4D replacement ECU. Will I need to also buy the ignition & key to match the replacement ECU?

[Rob58]

Hi. My 57 plate Yaris 1.4 D4D won't start after being layed up for 8mth. I got it checked out with a snap on reader & was advised the ECU needed replacing. I've found the correct matching ECU 2nd hand. Would I need to buy the ignition & key with the 2nd hand ECU? Any help appreciated

[Madasafish]

ECU failure is very rare.

Try charging the battery first.

The Battery voltage - with engine and ignition OFF_ should be 12.4V or more.

And less and the Battery is dead

[flash22]

New Battery - Flush the fuel system drain any water off the filter and prime it

Make sure the in tank pump is working, cars do not like to sit

 

As above ecu's just dont just stop working, the fact that they are able to communicate with the ecu is a good thing

[Mooly]

+1 The ECU would be the very last suspect here.

[aXeL_UK]

Why were you told the ECU need replacing, was it giving a specific error?  And which one, the ECU behind the glove box ( in car electronics ) or the actual PCM in the engine bay ( engine sensors and drive systems )? The latter might make more sense.  I'm only curious because my PCM needs replacing but in my case it's because it's started generating garbage diagnostic data and forcing limp mode randomly.

ECU failures are rare but they do happen.

Assuming my diag manuals are the right ones, when you plumb in a new PCM ( if I recall correctly ) it has to be given certain parameters about the car, e.g. the VIN needs to be entered, however it said nothing about having to change the locks.  However, if it's the cabin ECU behind the glove box, then it maybe the case.

This is why it would be handy to know what errors, if any, your scanner is giving you.

[stantheman1]

2 hours ago, aXeL_UK said:

Why were you told the ECU need replacing, was it giving a specific error?  And which one, the ECU behind the glove box ( in car electronics ) or the actual PCM in the engine bay ( engine sensors and drive systems )? The latter might make more sense.  I'm only curious because my PCM needs replacing but in my case it's because it's started generating garbage diagnostic data and forcing limp mode randomly.

ECU failures are rare but they do happen.

Assuming my diag manuals are the right ones, when you plumb in a new PCM ( if I recall correctly ) it has to be given certain parameters about the car, e.g. the VIN needs to be entered, however it said nothing about having to change the locks.  However, if it's the cabin ECU behind the glove box, then it maybe the case.

This is why it would be handy to know what errors, if any, your scanner is giving you.

Have you checked the network ie can high and can low? It could just be a network issue.

 

@OP

The ecu would be the last suspect as others have mentioned, check ALL ground/earthing points.

[stantheman1]

Is the switch on the clutch pedal working when it's depressed?

[aXeL_UK]

1 hour ago, stantheman1 said:

Have you checked the network ie can high and can low? It could just be a network issue.

You mean to the OBD itself? Good question: No.  I also get, often, a P0487. Correct me if you disagree but I would've thought it unlikely the engine would sporadically throw a P0487 for a network fault on the OBD connection.  The TPS, TB Actuator, Pedal potentiometer have all been checked with my multimeter and ruled out and both the EGR, TB and main engine harness replaced, all by Toyota, including cleaning the grounding.  That basically leaves the PCM unless I've missed something obvious.  MAF and MAP all read fine with the scanner.  Today my Load% gave no data until I turned off and restarted the car, then it read normally for idle and loading.  PCM reports the TPS stuck exactly at 3.1% but the car drives fine.  Some days it thinks 45%-49% even though the car drives normally.  Very very occasionally, it will report a normal % range, i.e. 3%-~55%.  It only reports the P0487 if it 'thinks' the TB is stuck near fully open, i.e. 45%-49%.  When it's stuck on 3.1%,  I don't get the MIL.  Seems to make sense; I read in the wiring diagrams that when the PCM logic can't reconcile the MAF, revs and TPS data,  it will complain because it thinks one of them is faulty.

 

@Rob58 - sorry, I've usurped your question!  Are you making headway?

[stantheman1]

@aXeL_UK

Could still be a network issue as they can cause intermittent issues like the ones you're having.

Do you have access to an oscilloscope? If so check the waveform and look for missing or unstable blocks.

With your multimer check the ohmic value on the obd2 port on pins 6 and 14 (can High and can Low) these can be back probed, it should be in the region of 60 ohms.(with ignition off) 

[aXeL_UK]

I didn't know that - thank you kindly, I'll give that a check.  Alas my last CRO died years ago but I can check resistance with my trusty multimeter. Never occured to me for a second that a faulty network connection might give a MIL for a powertrain fault much less EGR and it would certainly explain why no faults were found anywhere and, the big one, the car still driving fine! 

[stantheman1]

Please post back with your findings Andrew.

Not heard back from the OP though.

[aXeL_UK]

Sorry for the delay, frustated by the error code going away for a few days!  Ok, it's great that I don't get the error and the car isn't going back into limp mode but... still, I only 3.1% reported on the TPS, under any driving or idle.  Resistance is 61.1 ohms across Can Low and Hi.  Obviously without a CRO I can't check the voltage range when the car is running.  It's just weird that some data I used to get is gone now or only comes sporadically or comes but it just wrong.

[flash22]

what's the power like to the EGR an intermittent fault on the EGR may be pulling the voltage down, it may have tested fine in a workshop, P0487 is a EGR fault not TPS

Check for pin fitment issues, remove the EGR and clean it with carb cleaner they get heavily coked up

The ECU handles security it needs to see the correct information from the cars modules inc the cluster, network gateway and receiver

I will see if i can pull up a diagram

[stantheman1]

Thanks for the update Andrew.

It would be interesting to know the value of can H and can L with the error code or when in limp mode, but approx. 60 ohms is spot on.

Also have you checked the throttle body as these tend to 'cack' up as well as the egr as Bob points out?

It does seem weird that the tps only registers 3.1% regardless of load, have you checked this with key on engine off to see if it changes when you press the accelerator (typically should be approx. 16% at idle and go up to 85% at full throttle)? 

[aXeL_UK]

Hey Chaps, thanks for the feedback:

@flash22 - Good observation.  I should've mentioned that the EGR has been ruled out, it's been replaced with a brand new one by Toyota.  They also advised that the old one was in good condition but I decided to keep the new one anyway.  Moreover, they've replaced the engine wiring harness and the throttle body.  They drove the car and 15min later the P0487 came back.  Correct me if I'm mad, EGR wouldn't explain why TPS reading stays at 3.1% but the car drives fine.  Months ago, the TPS went through a phase of only reading between 45%-49%, i.e. as if the throttle was stuck open but, the car drove fine ( limp mode P0487 notwithstanding ).  Back then the P0487 was permanent rather than sporadic.  Also, back then, Load% was always null.

@stanthemen1

I suspect the TPS is fine and not just because it's a new one.  My reasoning being that, if the car drives fine ( when not being pushed into limp by a P0487 ) and, for the last couple of days not in limp mode at all, with a TPS reading ( from the PCM ( or indirectly from another control unit if the CAN bus isn't directly off of the PCM? )) of still 3.1% then the TPS is likely giving the PCM the correct signal voltage range and the PCM is using it correctly to fuel the car. That said, I will check across Can High and Low resistance whilst it's running.  TPS supply voltage is steady at 4.99V and 11.92V for the drive voltage to the actuator.

 

So why does an ECU report 3.1%, sporadic P0487 and, occasionally, it will refuse to give a Load% reading ( but the car will drive fine except for, sometimes, going into limp mode ).  For the Load% null value if I turn the car off and restart it, I sometimes start getting a reading.  I presume that, if the PCM was actually reading 3.1% for the throttle body, e.g. through duff signal voltage ( missing my CRO! ) it wouldn't tip any more fuel in to even let me drive the car because it would think the throttle body is almost closed.  However it knows the throttle body is open, either because it's getting correct signal voltages ( unless both TPS' were duff to the exact same extent ) or because it's reading things like MAF, rpms, maybe MAP, CPS ( I speculate here, having not gone into the depths of the control logic ) and inferring that the throttle body is working despite dodgy TPS data.  However.... exactly the same % TPS reading from two separate throttle bodies, matching to 0.1%?  Unlikely the TPS has a problem just as flash22 has pointed out.  If the supply voltage to the TPS was duff, I might've believed it.  The P0487 can be forcibly removed by disconnecting the TPS ( but leaving the TB actuator connected ).  It's replaced by another code, I can't recall which because, for some idiot reason I didn't write it down but it is similar in meaning to a P0487 in that it talked about the throttle circuit being open - i.e. pretty much what I would expect with a TPS disconnected as I've just opened the circuit.  As soon as I reconnected the TPS, the new error went away and the P0487 came back.

So assuming I don't have two broken throttle bodies/sensors or two broken wiring harnesses or two broken EGR units, unless there's something really bizarre and hinky about how the control logic works with MAF, MAP or lambda data to infer an EGR problem ( speculating wildly and random here, I'm just highlighting my lack of knowledge as to how the control logic has been programmed and with what thresholds to trigger a P0487 ).  If I had the source code to the ECU I bet we could pin this down in about five minutes.

 

[aXeL_UK]

15 hours ago, stantheman1 said:

Thanks for the update Andrew.

It would be interesting to know the value of can H and can L with the error code or when in limp mode, but approx. 60 ohms is spot on.

Also have you checked the throttle body as these tend to 'cack' up as well as the egr as Bob points out?

It does seem weird that the tps only registers 3.1% regardless of load, have you checked this with key on engine off to see if it changes when you press the accelerator (typically should be approx. 16% at idle and go up to 85% at full throttle)? 

Sorry, should've mentioned, 3.1% is consistent whether the ignition is just on or if the engine is actually running.

Also, when I turn the ignition off, TPS will blip to about 94% and then, over the course of ~2 sec, drop to 3.1%.  At first I thought this might just be surge but, hang on, what the CAN sends is packets of network traffic so a voltage spike wouldn't be interpreted as packets of increased TPS data.

It had made me wonder if my scanner was duff but I've tested it on a Clio and an Astra and it shows normal behaviour.

[flash22]

what is the mileage ?

There are 2 tps A and B

The A side is the throttle pedal these a can wear in 1 spot and give all sorts of strange readings, you can check the resistance and voltage range

I will have to look at some wiring diagrams and work out what else is grouped with the EGR

 

Edit. You can send your ecu off for testing there are a few companies that do it

 

 

[aXeL_UK]

Mileage is ~120,000 miles.  I changed the throttle pedal for the sake of testing with a different pedal potentiometer but the error didn't go way unfortunately.  However.... it was technically the wrong gas pedal.  It was from an Auris of the same year. Whilst, the plug fitting was the same, it was a different part number and mount type so it's conceivable that it wasn't a good test.  Not been able to find an exact pedal from a breakers yard.

If you have a list of what's grouped with the EGR that would be most helpful.  I've been trawling close to a thousand pages of wiring diagrams but ( a ) I'm not convinced I'm reading them all correctly and ( b) Not all of them are for my exact car so I have to guess in a few areas.  Interesting to note that some throttle bodies have sensors to to detect failures in their own sensor.  Why would they design it that way if it wasn't a known weakness?!  Mine, however does not appear to be designed that way.  Those ones all have six pin plugs if I recall for both the actuator and the TPS, whereas mine has two three pin plugs.  However I could be reading it wrong.  But I guess it's still mooted by both your previous point and the fact that I'm on my second one.

The only reason I got hung up on the TB and the gas pedal was because, other than the actual EGR, I can only guess what might be relevant and I'm almost worried that the P0487 is being used by Toyota as a generic powertrain code when the PCM doesn't really know where the fault is.  Be much happier to be shown I'm wrong.

 

[aXeL_UK]

I have thought about sending the ECU off for testing.  For my weak hands, where it's mounted in the engine bay against the firewall, it's a pig to get to.  I can just about put my hands on the connectors but can't get near the attachment point for the bracket.

Plus, in my own and, sadly, my family's experience; ECU specialists have never been able to fix ECU problems but they still charge a few hundred quid each time for not fixing the problem.  Last time being my brother in law's ancient corsa with no signal on the K-line for the immobiliser.  Sorry it we didn't fix it and we're keeping your money but you can spend more and we'll look at it again.  I don't trust these people, I reckon that's why they charge so much to just 'look'. - They know most of the time they can't do anything.  But that's just my own perception.

I had an ECU on back order from Toyota since March but they can't get one.  I chased them once a month but they finally admitted they don't know 'if' they can get one, much less when.  Then I was hopeful it might not be ECU at all but it's starting to feel more and more likely an ECU failure.

[flash22]

Have you checked the throttle valve body ?, i see something in one of your older posts

It's is the elbow on the intake that the TB and EGR bolts to, a air leak will cause issues

17861-33020

 

[Cyclopse11]

1 hour ago, aXeL_UK said:

I have thought about sending the ECU off for testing.  For my weak hands, where it's mounted in the engine bay against the firewall, it's a pig to get to.  I can just about put my hands on the connectors but can't get near the attachment point for the bracket.

Plus, in my own and, sadly, my family's experience; ECU specialists have never been able to fix ECU problems but they still charge a few hundred quid each time for not fixing the problem.  Last time being my brother in law's ancient corsa with no signal on the K-line for the immobiliser.  Sorry it we didn't fix it and we're keeping your money but you can spend more and we'll look at it again.  I don't trust these people, I reckon that's why they charge so much to just 'look'. - They know most of the time they can't do anything.  But that's just my own perception.

I had an ECU on back order from Toyota since March but they can't get one.  I chased them once a month but they finally admitted they don't know 'if' they can get one, much less when.  Then I was hopeful it might not be ECU at all but it's starting to feel more and more likely an ECU failure.

This explains why you are still having issues, unable to get a new ECU. I know about ECU accessibility, the fuel filter is in the way!

I am still having issues too! I had the EGR deleted from the ECU and blanked off just before the cooler but still having issues. I get no error codes or EML but car is stuck in limp mode. Runs great up to 3000 rpm with good turbo boost. But will not rev any further. I am sure we are both suffering the same issue. Is it a faulty ECU or has something broken down causing limp mode?

Regards

Cyclopse

[aXeL_UK]

Now that is an interesting question.  Toyota said they found no indication of a leak, however.... my MAP rarely reads below 98KPa even if I suddenly close the throttle, which would imply a leak to me but they said they couldn't fine one.  That said, I would've thought when the EGR and TB were replaced, they'd have looked at the elbow then.

But then, if there is a leak, I get none of the driving symptoms whatsoever; idle is fine, acceleration is fine, no hesitation and the smoke test found nothing.

[flash22]

Old school way would be start the engine and spray a bit of carb cleaner around the joints if it revs or stutters/dies its pulling it in

 

Did you see the smoke test done ?

 

Just for laughs, have you tried pulling the ABS fuse

[aXeL_UK]

Steve, your car goes into limp mode but doesn't give you any error codes? Personally, I wasn't aware one could have a check engine light without a corresponding code.

I've only seen that on a petrol naturally aspirated engine when the alternator VRM was on the way out.  The car wouldn't go over ~3000rpm but I don't think that applies here since you don't have spark plugs.  I don't know about Yaris turbos but on Imprezas, if there isn't enough tension on the waste-gate pre-load spring ( can't recall the exact name ), the waste gate can open too early and you lose top end boost.  A common misconception is that max boost is at max rpms but it's not, it's at max engine load which can be lower down the rev range.  I came across this whilst re-mapping Imprezas and going through the various fueling and timing maps ( not that you have a timing map ). A shot in the dark but maybe worth a look.  I don't know about AFRs on diesels; someone once told me that for more power on diesels, you just keep adding fuel but not until it blows up - sounds too glib to be true to me but then we were talking about our Merc OM642 engines which had turbos far larger than the engine could make use off so the addage might, kinda, been true. Ergo, is it not fuelling enough?

Bob has got me thinking about the mixture rather than the electricals.  I get that there are all kinds of codes for Cat and Lambda problem but I wonder if there's a threshold in there corresponding to the P0487.

Ah but Bob, the PCM telling me the TP is 3.1% and sporadic null readings for Load%:  I don't get how a leak would explain network traffic either not being generated ( Load% ) or the same fixed value ( TP%) on the CAN bus for those components.

 

[flash22]

tps and egr are directly controlled by the ecu, if there is a can bus issue you see it with a scope on the DLC a common culprit for causing CAN issues is the ABS

You also have a Lin bus

What scan tool are you using ?