2.5tdi won’t start - weird modulating piston movement sensor voltage readings


New member
Apr 3, 2021
Hi, I really hope someone on here can help me get my 2000 2.5tdi T4 Transporter (Uk) running again. I’ve just had a freshly refurbished injection pump installed and timed by a specialist using a dti gauge. TDC was correctly set on cam. He did the work on my driveway as getting my LWB high roof van to him was going to be a problem.

The fault I’m getting in VCDS lite is “modulating piston movement sensor electrical malfunction”: 17762 - P1354 Modulating Piston Movement Sensor (G149): Electrical Malfunction

This is the same fault I had before concluding the my previous injection pump needed replacing (which in hindsight now may not have been faulty after all...).

My van will crank but not start. I’ve checked all the resistances & loads on the wires from ECU to ten pin pump connector and from ten pin connector to pump. All are in spec. I’ve also checked the voltages at the connector with ignition on - these are the results at the ten pin plug.

Quantity Adjuster testing at ten pin plug:

Pin 1 & 2: 4.9 - 7.5 ohms result 6.9
2 & 3: 4.9 - 7.5 ohms result 6.9
5 & 6: 0.5 - 2.5 ohms result 1.2

Pin 1 voltage: 2.52v
Pin 3 voltage: 2.52v
Pin 5 voltage: 12.53v
Pin 7 voltage: 5.01v
Pin 10 voltage: 12.51v

Needle lift sensor has no fault and resistance is in spec. Glow plug light illuminates and all five get battery voltage on ignition. Fuel pump has been primed - I fitted an in-line hand bulb primer. Crank sensor is working because VCDS shows rpm values when trying to start. Replaced 109 relay and swapped in my spare ECU. Same fault code and non start.

I videoed VCDS measuring blocks 001, 004 and 019. What’s confusing is that in 019 both start and stop voltages for the modulating piston movement sensor are 5v - another T4 owner sent me a video of his running and the values are 0.740v and 4.640v.

Why would my readings both be static at 5.040v If the voltages at the plug for the Quantity Adjuster pins 1 and 3 are 2.5v?

Also, in measuring block 004 Actual Injection Quantity shows 0.0 BTDC with a duty cycle of 94% which drops to 54% on cranking even though the timing has been set at .55 with a dti gauge? Is that just because it’s actually not running and engine not up to temp soots a red herring?

I hope somebody can help point me in the right direction and solve this. Thanks

Video of readings trying to start: VCDS measuring blocks