Is this a faulty ECU? V6

[Iwannabongo]

(V6 Petrol 2000)
Hi all,
I have posted this problem here before, but have now eliminated a couple of things. Any help much appreciated

Everything always works fine on initial start up and continues to do so until engine is turned off.
Once restarted speedo stays at zero and autobox selects 3rd gear and doesn't select any other gears.
Hold button, S or L gears won't engage.
Hold button does not flash.
ATF fluid OK.
No speedo chip is fitted behind(kph to mph).
No relevant fault codes showing.
This carries on doing this until it seems the engine is cold again.
Speed Sensor checked and is OK.
Before spending out on a replacement ECU, could there be any other things to check?
thanks in advance for any info

[teenmal]

Hi Iwannabongo,

It could well be the ECU etc etc etc,the first thing that I would do is check the connectors on the ECU.Then disconnect the battery/s and depress the brake pedal (turn on headlamp switch)to reset the system.

Cheers..

[mikexgough]

Hi Iwannabongo,

It could well be the ECU etc etc etc,the first thing that I would do is check the connectors on the ECU.Then disconnect the battery/s and depress the brake pedal (turn on headlamp switch)to reset the system.

Cheers..

I also leave the battery disconnected for 30 mins.....have a cuppa..... so all is cleared.... then everything is at factory default... Sometimes the disconnect/reset is not enough.... been there done that in the past.....

[Iwannabongo]

Hi teenmal,
thanks for reply.
I have tried disconnecting the battery and pressed brake pedal to reset the ecu, but still no luck.
As it is not an intermittent problem while driving I presume all connections would be OK as it only happens when engine is restarted.

Mikexgough, I have only disconnected battery for a few minutes to reset, but it is on a charge as we speak, so will have my fingers crossed when I reconnect it, but I think this is a bit hopeful

[g8dhe]

The speedo is not driven from the ECU, its driven directly (or via chip for mpg) from the sensor (speed meter) C2-03;

The output from the speedo is sent onwards to the ECU via diagram link 52, and several other places as well.
The Tacho is driven from the ECU, but that is driven from a sensor in the distributor I believe.

If the above is right then if the Speedo is not reading correctly I would look at the sensor C2-03 and wiring back to the display first.

[teenmal]

Hi Geoff,

Is it possible that a speedo chip(converter)has been fitted to somewhere other than at the rear of the instrument cluster PCB.

I have heard of chips being fitted (have not seen it) at the gear box?.

Cheers.

[g8dhe]

I can't see any reason why it can't be fitted somewhere else, it only needs to intercept one of the sensor connections and be fed with 12v and earth, what does the Speedo read Kms or Mph ? Oh and is it the standard dashboard not one with a different display markings for Mph ?

[Iwannabongo]

I can't see any reason why it can't be fitted somewhere else, it only needs to intercept one of the sensor connections and be fed with 12v and earth, what does the Speedo read Kms or Mph ? Oh and is it the standard dashboard not one with a different display markings for Mph ?

Hi geoff,
it has replacement dials that are reading in mph.
As the fault is with the gears and speedo I presumed this could be the ecu

[teenmal]

Hi Iwannabongo,

Does your odometer and trip read Kilometers or Miles.

Cheers.

[g8dhe]

If the Speedo isn't displaying any reading then that isn't dependent on the ECU at all. However the ECU is dependent on the pulses coming from the Speedo, so it points to a problem from the sensor thru to and including the Speedo module.
How was the sensor checked and which one was checked specifically ?

Edit: There are TWO speed sensors one feeds the display (C2-03) and the other feeds the Transmission Control Module (H-04)
The position of the connectors are H-04;

and C2-03;

They are close together.

[g8dhe]

Just noticed that your a Year 2000 vehicle, so the diagrams may not be correct as they only cover 95-99, but I wouldn't think that the display console will change much.

[Iwannabongo]

Geoff-
I took it to a bongo specialist, but he is waiting to try and get parts off a V6 to try out, as he has only got diesels and a pre 99 ecu. I thought if I could pinpoint it to the ecu then it would be worth getting a spare one to get him to fit, but obviously don't want to spend out £100+ to find this isn't the problem.

[Iwannabongo]

Hi Iwannabongo,

Does your odometer and trip read Kilometers or Miles.

Cheers.

Kilometers

[g8dhe]

Yup the H-04 one doesn't feed the Speedo so that would make sense that there wasn't any change, I think its the C2-03 sensor that needs looking at. Not quite sure where that is placed exactly, there is one sensor here 21-5H2; http://lushprojects.com/bongopartsmk2/c ... o=.html#65 but I'ts not clear which one it is.

[Iwannabongo]

Sorry, it could have been either of them that was replaced. I looked at H-04 diagram and didn't see the other sensor was in the same position.