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[mertcanberal]

Hi all,

Looking for anyone who has been through something similar. Vehicle details first:


Model: Opel / Vauxhall Omega B, 1996
Engine: 2.0 16V, engine code X20XEV
Gearbox: 4-speed electronically controlled automatic, AR25
Fuel: petrol + LPG
Original engine management: Simtec 56.1 (ECU + harness)
Now running: Simtec 56.5 ECU with a brand-new compatible Vectra B automatic loom


Background. The car was originally on Simtec 56.1. We hit two problems at the same time: parts were getting hard to source, and we had faults we simply could not clear. On the old 56.1 ECU and harness the engine would not run properly even after trying and replacing every relevant sensor, and we could not get any OBD connection at all.

To get past both the parts situation and the dead-end faults, we did a full swap: a Simtec 56.5 ECU together with a compatible brand-new Vectra B harness. We kept the car's original Omega AR25 gearbox and its transmission control unit (TCM).

Result. The engine now starts and runs really well, OBD connects and reads fine, and in general everything is OK. But three things are still not working:


Rev counter (tachometer) is dead. Needle does not move at all.
Instantaneous fuel consumption shows 0 L on the trip computer.
The automatic will not shift above 1st gear, not even in manual mode. Only 1st and reverse work.


So the engine side seems happy, but it looks like a few signals are not getting where they should after the swap: the rev-counter signal to the cluster, the consumption / injection signal to the trip computer, and the engine-to-TCM interface needed for shifting.

Questions:


Has anyone done a 56.1 → 56.5 swap on an Omega B auto, or run a Vectra B loom on an Omega AR25, and hit the same tacho / consumption / no-upshift combination?
On the 56.5, which ECU pin actually outputs the rev-counter signal, and where does it land on the cluster?
How should the 56.5 feed engine speed, load and the torque-reduction line to the AR25 TCM, given the 56.5 pinout differs from the 56.1?


Any pinouts, wiring notes or "been there" experiences would be hugely appreciated. Thanks in advance.

[TheBoy]

The gearbox issue is likely because the 2 ECUs do not understand each other's configs - these 2 ECUs (Simtec and TCM) work closely together.Not sure if there is an Omega variant code (code index in GM speak) for that Simtec, if not, you are  unlikely to succeed.

Another immediate thought is if the (Simtec) ECU has a fault not outputting RPM, hence both the tacho and the autobox not working.


I'm not aware of anyone putting a Vectra ECU and loom into an Omega