1999 Disco 2 V8 auto HDC and TC lights after engine ecu replacement

Just brought the car a month ago. Replaced the ignition coil packs, plug leads and spark plugs as engine originally lacked power and I could see that the plug leads were breaking down as I could see the leads arcing at night. Also replaced exhaust downpipe gaskets as they were blowing. Once I fixed these problems it highlighted a problem with the engine ECU. Replaced engine ECU due to fault that was causing multiple misfires and lambda readings to go to a static level some time after startup. Engine is now running fine but dashboard is now displaying the hill descent control (HDC) and the traction control (TC) lights immediately after startup. According to the workshop manual this equates to one of the following faults:-
Sticking throttle pot.
Loss of signal.
Data corruption.

Took car for 10 mile test run and engine run fine and no engine fault codes came up when I plugged in the Hawkeye tester.

Connected an oscilloscope to pin 6 (grey wire with purple stripe) of connector C0203 in the engine bay (grey connector near the fuse box and brake servo) and a PWM signal switching between 0 and 12V was being displayed and the mark - space ratio changed when the throttle position was altered.

I have checked that all of the brake lights work correctly.

Could the engine ECU be incorrectly programmed so that the SLABs ECU does not recognise the signal?

Any suggestions as to what could be causing this fault?

Took car for 10 mile test run and engine run fine and no engine fault codes came up when I plugged in the Hawkeye tester.

... Connected an oscilloscope to pin 6 (grey wire with purple stripe) of connector C0203 in the engine bay

Click to expand...

but didnt you read the SLABS ECU aswell? ...and why do you need an osciloscope if you have hawkeye? you can read the TP sensor's outputs on live data

and make sure that the replacement ECU's driver demand(TP sensor output) is set as it was the previous one, for 2 or 3 track sensor according to the modell(see the TP sensor description in the workshop manual -engine management) ... u can set the driver demand with hawkeye in the EMS-programming menu

I only have a Hawkeye diagnostics unit. I do not believe that I can programme settings with this. I cannot see anything in the options menu. The engine ECU was programmed in by a neighbour using a Autologic unit. I do not remember this asking for throttle pot type settings.

The Hawkeye is showing throttle position via the SLABs ECU. I used the oscilloscope to see if the voltage levels were low or if there was a lot of noise on the line which could cause data corruption.

The throttle pot is a Bosch 0280 122 016. I could not see anything in the workshop manual regarding 2 and 3 track sensors.

:frusty: ...sorry...i just realised that yours is V8 not Td5...disregard the TP setting then ...unfortunately the V8 is not my strong point to help you

So what faults are stored in the SLABS ecu ?

Fault 4021: Failure of the throttle position signal.

If you are happy that the cabling twixt engine and Slabs ecu's are good,And that the engine ecu is running the engine properly, I'd be suspecting the software download from the Autologic.Was the tune sent down specifically for this Vin - or was it just a tune he already had loaded on it ?
I'd rather trust a tune direct from Testbook,from memory the Bosch ecu's can be reflashed up to 80 times.

The tune was set against the vin number and the programmer immediately recognised that the engine ECU was a new unit. Reading the live data from the SLABs ECU it is showing the throttle position and the engine load. Took car for short test drive with a mechanic in the passenger seat monitoring the SLABs ECU data and could not see anything wrong from the sensor readings. Looks like the ECU will have to be reprogrammed. It is annoying that there is no obvious fault (apart from the two dash lights which will not go out).

Tested today with a T4 system and it came up with a software mismatch problem between the engine ECU and the SLABs ECU. ECU reprogrammed using this system and now everything appears to be working correctly. Now need to give it a long test drive to see if all of the gremlins have left the system.

Good job its sorted,Testbook has been moaned about endlessly,(Mostly by people who dont know or have interests in other kit...) BUT - it works,properly.Been using it daily since 2003 when it was first made available to independants.Never had a problem programming an ecu with it.