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Discussion Starter · #1 ·
2000MY Transporter 2.5L Petrol AET manual gearbox- I just purchased this vehicle with these known issues and need to sort it out, any helps is greatly appreciated! I have replicated these errors and will describe them below:

The vehicle will just turn off randomly, either hot or cold, and fails to restart for 5-20minutes after the fault occurs.
The oil lamp blinks and a loud series of BEEPs are heard immediately after the power loss if cut out occurs (while engine running).
Sometimes if it has been switched off while hot, it just fails to start until it cools a bit.

The VAG COM Spits out the following:
1. 520 - Volume Mass Air Flow Sensor - G19ig79
2. 513 - Engine Speed Sensor
3. 520 - Volume Mass Air Flow Sensor - G19ig79
4. 537 - Oxygen Sensor Control

Not sure why it ready 520 twice. The exhaust definitely has some audible leaks, so the O2 sensor issue doesn't surprise me.
513 would indicate a signal malfunction from the Hall Effect Sensor, I am guessing? I will definitely replace it as soon as I can get a part, but have a hunch that might not be "it".

I have read some posts about checking ECU ground cables as well as the Relay 30 and 167 (ECU power and Fuel Pump respectively). I loosely checked Relay 30 for functionality, and even re-soldered some of the joints to make sure, but no change in outcome. I will check the Fuel Pump Relay next as well as examine the ground wires.

It appears the ignition coil has been checked as there is a second one in the vehicle, and the one installed has "good" written on the side of it.

its a difficult one to diagnose as it randomly will cut off and leave you on the side of the road, not the best place for troubleshooting. Also the window for trouble shooting is often over within 10 minutes, as the vehicle mysteriously becomes totally functional again.

Any feedback on what to look for would be greatly appreciated.


Thanks-

jasshrie
1. 1991 T4 2.4D Caravelle
2. 1995 T4 2.5 Petrol Eurovan - LPG conversion
3. 1995 T4 1.9TD Multivan Allstar
4. 1998 T4b 2.5TDI Multivan
5. 2000 T4 2.5 Petrol Transporter
 

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Discussion Starter · #2 ·
I can confirm that during the "non-restart" after the vehicle cuts out, the ECU relay 30 in position number 3 is audibly clicking as well as the fuel pump relay in position number 12, and with both I can "feel" the click by placing my finger on them. Sometimes the fuel pump relay does chatter for half a second or so. Is that indicative of the relay failing? or possibly of a bad ground or something else? I will pull out the relays today and check both, but need to initiate the cut-out failure to accurately test them, so will make a mobile testing kit to take on a "test drive" so that I can induce the failure.

Any feedback greatly appreciated.
 

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Hello mate from you described it sounds like you are losing the main feed from the ignition switch
If so the electrical part of the switch is a cheap part and easily replaced
 

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Discussion Starter · #4 ·
Hello mate from you described it sounds like you are losing the main feed from the ignition switch
If so the electrical part of the switch is a cheap part and easily replaced
If it were the ignition switch, wouldn't it not turn the engine over at all? It acts like its not getting fuel or spark, just turns over without firing.

Thanks!
 

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those symptoms, are usually caused by a failing crank sensor, the problem is it dont log a fault cos it starts afterwards,
could also be hall effect sensor, but crank sensor has a hard lfe,I would try changin it, they aint to expensive
 

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Two separate outputs mate
The symptoms were more than one pulsing relay
Turning on you ignition Switches these relays on
That's were I would look first Sounds like a faulty connection somewhere in that circuit Good luck
 

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Discussion Starter · #7 ·
Dug a little deeper today, was able to test both relays and they seem to be functional, even when the fault is occurring, which leads me to look elsewhere.
NOTE: When the engine cuts out, it takes some time to be able to start, and that is the time when the troubleshooting must occur, which is normally on the side of a busy road somewhere.

1. Jumpered the fuel pump relay just to test it, and it still did not start (could hear the fuel pump running).
2. After some minutes, it seems that I heard an audible "click" from somewhere other than the relay/fuse panel. After the click I turned the key and she started right up.

When I was back at my workshop I tried to induce the issue after verifying that the DTC codes previous were flagged again (they were - MAF, O2 Sensor, Crankshaft Position Sensor- sub-note that the CPS error is rarely induced).

1. Started with the MAF, unplugged it, and there was absolutely no change in the engine operation at idle or revving.
2. Next the Hall Effect Sensor, unplugging or starting with unplugged made no difference.
3. As soon as the Crankshaft position sensor was unplugged, the engine cut out, and was unable to restart with unplugged.
That seemed to give me an indication that it may be the issue, but this was unable to flag a DTC code.

I measured the signal from the CPS when it was functioning, but was unable to induce the cutout while normally driving so that I could diagnose and measure the signal at this time. Thanks for the tip vwtoy .I'll try again tomorrow.

Does anyone by chance know the part number of the CPS for the 2.5L Petrol AET engine?
 

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Discussion Starter · #8 ·
Dug a little deeper today, was able to test both relays and they seem to be functional, even when the fault is occurring, which leads me to look elsewhere.
NOTE: When the engine cuts out, it takes some time to be able to start, and that is the time when the troubleshooting must occur, which is normally on the side of a busy road somewhere.

1. Jumpered the fuel pump relay just to test it, and it still did not start (could hear the fuel pump running).
2. After some minutes, it seems that I heard an audible "click" from somewhere other than the relay/fuse panel. After the click I turned the key and she started right up.

When I was back at my workshop I tried to induce the issue after verifying that the DTC codes previous were flagged again (they were - MAF, O2 Sensor, Crankshaft Position Sensor- sub-note that the CPS error is rarely induced).

1. Started with the MAF, unplugged it, and there was absolutely no change in the engine operation at idle or revving.
2. Next the Hall Effect Sensor, unplugging or starting with unplugged made no difference.
3. As soon as the Crankshaft position sensor was unplugged, the engine cut out, and was unable to restart with unplugged.
That seemed to give me an indication that it may be the issue, but this was unable to flag a DTC code.

I measured the signal from the CPS when it was functioning, but was unable to induce the cutout while normally driving so that I could diagnose and measure the signal at this time. Thanks for the tip vwtoy .I'll try again tomorrow.

Does anyone by chance know the part number of the CPS for the 2.5L Petrol AET engine?
Just to clarify the above:

CPS (or engine speed sensor) part number listed on the cable is "026 906 433 A" but I cannot find this part at any of the parts shops online or on ebay...

Fuel Pump Relay Box Plug Location voltage checks (using chassis as earth-ground) with ignition on and ECU relay installed gave the followingresults:
Position 2 (pin 86) = 12.56V (battery Voltage)
Position 3 (pin 85) = 2.15V
Position 4 (pin 87) = 0.0V
Position 6 (pin 30) = 12.56V (battery Voltage)

The CPS check done while vehicle was functional, removing the fuel pump relay to avoid start, and while cranking showed this expected square wave form, with the difference at ~10V.
 

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Don't if this is any help on mine relay 3 (30) clicks on with ignition, when left with engine not running and key turned off after a minute you hear/see it click off
 

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Yeah mate It can be very difficult to troubleshoot an interrmittant problem A quick test when you have the problem is to spray some easy start or throttle body cleaner down the intake If it starts and runs temporarily this will point in the direction of fuel delivery
 

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..................
3. As soon as the Crankshaft position sensor was unplugged, the engine cut out, and was unable to restart with unplugged.
......................
Doesn't Crank sensor give TDC to ECU? so no sensor - no TDC - no ability to fire at the right time.
Also you mention a click that seemed to coincide with the ability to start I would not have expected any click triggered from Crank sensor as surely it is simply a trigger signal and would be to timing critical to drive via a relay.
All IMHO of course.
My wife's car seems to eat Crank sensors but only symptom is poor starting, once running its OK.
 

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Discussion Starter · #13 ·
Re: 2.5L Petrol AET - Cut out problem... SOLVED

those symptoms, are usually caused by a failing crank sensor, the problem is it dont log a fault cos it starts afterwards,
could also be hall effect sensor, but crank sensor has a hard lfe,I would try changin it, they aint to expensive
Thanks vwtoy, I grabbed a used CPS from the junkyard to have in the car just in case. I never got to try to measure the signal from the CPS during one of the "cut off" events, as I never had someone in the car to crank it while I got underneath, so during an event on Thursday morning, I just popped the used CPS in and removed the original one. The engine started right up and has not "cut out" since. I had also replaced the vacuum lines to the fuel pressure regulator and EGR valve the day before (old ones where falling apart, and probably leaking).

There are still some issues with the engine, but the "cut out" issue seems to have been correctly identified as the Crankshaft Position Sensor (CPS).

I would call this issue solved. Thanks to all who posted!
 

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Hey Thats great news,lets hope it stays good,cps is a pain as if it breaks down and stops the motor, then starts it leaves no code as the "fault" is no onger there!

would say however you will get no output unless the motor is being turned by someone while you measure it,but they do have a regular habit of getting hot then cutting out,cooling down and then it restarts as if nothing was ever wrong
 

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Hi!
This is my very first post here, so please be kind... :)

I'm having an identical problem with my T4 -97 AET - and I've been googling and googling and googling but I can't seem to find any information.

And I have no immediate access to my car as of now either.

So I'm back here again...writing my first post... I:

Two primary questions:
> Is there really a Crankshaft Position/Engine Speed sensor on the AET?!?

A rather absurd question given what this thread says - but the true lack of information (or contradictory at best) on the web makes me wonder. And since I can't dive into my own car right now - but still need to lay out some plan...well... :confused:

> Where the heck is it located...? :(


I will also need some information about how to correctly diagnose (measure) the infamous Relay 30 - but I believe there's an abundance of info about that one, so I'm sure I'll find something that can tell me if I've measured it correctly or not. :D

So, if anyone reads this - please give me some clues?!
 

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Cars I've had CPS sensor issues with have had the sensor located either against the flywheel or against the cam shaft pulley.
Unfortunately I've had no experience re CPS on a T4 but cannot imagine it being anywhere else.
 
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