94 VR6 Non starter - Suspected ECU fault

[Reddy VR6 10]

Hi All,

The other morning my VR6 started first time, as it always does but then 3 minutes later just died. The car is now at a VW Specialists where they say there is no fuel coming through or spark. They have gone through the car and state that they believe the ECU is faulty. There is power at the ECU but other than that it is blank and they are unable to interrogate it or diagnose the fault. They sent the ECU off for testing but the company they sent it to said they were unable to test it, therefore they are trying to find another company that can.

I am no expert but it would appear that if the ECU is found faulty and can eventually be repaired then happy days. More other options seem to be to buy a second hand tested ECU from a reliable company and have the garage fit that in the car.

One question on the above is when you install a new replacement ECU for the first time in the car will it require special programming to get it up and running correctly ?

Are there any other common faults associated with the above problems I should get the garage to look into ?

If the ECU comes back fine then an Auto Electrician is going to have to go over the car.

Just to note after the car had conked out and been cranked over a few times the battery went flat and a local mechanic tried to jump start it but with no success. I am aware that jump starting these cars can cause problems but in this instance it appears the fault was already there.

If anybody has had similar problems before or can offer any advice around the ECU detail then that would be much appreciated. My ECU is the Bosch type - 021 0906 258 AG.

Thanks in advance.

 

[Dox 22]

When cranking do the rpms display on the tacho?

[James. 7]

Ecu relay ?

[fla 9]

3 hours ago, James. said:

Ecu relay ?

This.

No. 109. 

I would replace that first before doing anything else. It wont come up in a scan either.

[Cressa 43]

This problem is above me, but could it be an immobiliser fault! Just a thought. Mine has caught me out b4. Is it just a standard immobiliser  or is another fitted. 

Try and avoid jump starting, give the battery a good charge/ replace it with a known good one. They are delicate with this

Good luck

[fendervg 29]

ECU relay is first bet, also fuel pump relay. Also worth checking the crank position sensor. The ECUs rarely go faulty unless there is water damage or a wiring problem has caused a short or incorrect supply voltage.

There is no special programming required, if the part# is identical you can just pop it in and go - ideally you would do a basic settings procedure in VCDS once the car is warmed up and has been driven for a while to set the maps etc. correctly, but it will run fine without this.

You are unlikely to get a guarantee or anything with a 20 year old ECU at this stage, so your options are really to buy second hand and take your chances or or swap a known working one in to confirm the diagnosis. If VW Classic parts have one, they will be looking for an arm and a leg for it, you can be sure.

Worth trying the cheaper relay options first though.

[vw rule 19]

If your ECU is found to be at fault and you can't source a good replacement, I've used this company in the past they're called ECU TESTING, based in Derbyshire.  Once in contact with them they'll need all the numbers from your ECU, they'll then confirm if they've had that type in before, as some have fully encrypted software which they can't always decode to enable them to work on it, if this is the case and they can't decode it, they'll send it back to you free off charge including postage.

There's a testing charge of £45 + VAT that applies if no fault is found, plus postage as they'll send your unit back to you.

But if ECU is found to be faulty then the above testing charge/fee is waived,  and the repair charge is £195 + VAT + postage.

Prices are from early 2019 as that's when I used them last.

 

Contact details are below just in case you need them.

(email)  [email protected]

(Tel phone) 01773 535638

 

hope you get it sorted

si 

[James. 7]

Ecu relay can develop hairline cracks where the pins meet the pcb at the soldered joint. Leading to intermittent starting. Re-flow the joint. Certainly a cheap fix to start with.

[Reddy VR6 10]

On 6/12/2020 at 6:44 PM, Dox said:

When cranking do the rpms display on the tacho?

Thanks for replying. No the RPM's aren't displaying on the tacho when cranking. Does this rule out any particular issue ?

[Reddy VR6 10]

On 6/12/2020 at 8:10 PM, James. said:

Ecu relay ?

Thanks for replying. Yes seems quite an obvious one so I will make sure the garage have looked at that.

[Reddy VR6 10]

On 6/12/2020 at 11:18 PM, fla said:

This.

No. 109. 

I would replace that first before doing anything else. It wont come up in a scan either.

Great. I will get on to the garage with this info.

[Reddy VR6 10]

On 6/13/2020 at 9:01 AM, Cressa said:

This problem is above me, but could it be an immobiliser fault! Just a thought. Mine has caught me out b4. Is it just a standard immobiliser  or is another fitted. 

Try and avoid jump starting, give the battery a good charge/ replace it with a known good one. They are delicate with this

Good luck

Thanks. Yes I did think it could be the immobiliser first off but when my immobiliser is on you can't crank the engine over and the engine can currently be cranked over. The garage reckon they have looked into this but you never know. Agree reckon I should stick a new battery on there too.

[Reddy VR6 10]

22 hours ago, fendervg said:

ECU relay is first bet, also fuel pump relay. Also worth checking the crank position sensor. The ECUs rarely go faulty unless there is water damage or a wiring problem has caused a short or incorrect supply voltage.

There is no special programming required, if the part# is identical you can just pop it in and go - ideally you would do a basic settings procedure in VCDS once the car is warmed up and has been driven for a while to set the maps etc. correctly, but it will run fine without this.

You are unlikely to get a guarantee or anything with a 20 year old ECU at this stage, so your options are really to buy second hand and take your chances or or swap a known working one in to confirm the diagnosis. If VW Classic parts have one, they will be looking for an arm and a leg for it, you can be sure.

Worth trying the cheaper relay options first though.

Thanks for responding. Good info to know regarding the ECU's and I will make sure they have checked the relays too. As you say its best to replace rthe cheaper parts first !

[Reddy VR6 10]

19 hours ago, vw rule said:

If your ECU is found to be at fault and you can't source a good replacement, I've used this company in the past they're called ECU TESTING, based in Derbyshire.  Once in contact with them they'll need all the numbers from your ECU, they'll then confirm if they've had that type in before, as some have fully encrypted software which they can't always decode to enable them to work on it, if this is the case and they can't decode it, they'll send it back to you free off charge including postage.

There's a testing charge of £45 + VAT that applies if no fault is found, plus postage as they'll send your unit back to you.

But if ECU is found to be faulty then the above testing charge/fee is waived,  and the repair charge is £195 + VAT + postage.

Prices are from early 2019 as that's when I used them last.

 

Contact details are below just in case you need them.

(email)  [email protected]

(Tel phone) 01773 535638

 

hope you get it sorted

si 

Thanks Si, much appreciated. I will check them out and give them a call.

[Reddy VR6 10]

12 hours ago, James. said:

Ecu relay can develop hairline cracks where the pins meet the pcb at the soldered joint. Leading to intermittent starting. Re-flow the joint. Certainly a cheap fix to start with.

Cheers James. Good tip. Hopefully it will be a cheap fix !

[Dox 22]

35 minutes ago, Reddy VR6 said:

Thanks for replying. No the RPM's aren't displaying on the tacho when cranking. Does this rule out any particular issue ?

Unfortunately not