hi all just asking are ecus interchangable mines an h 4 for an 2.5 td estate my electrovalves are not working and after reading various posts realised that sport light dosent come on on switch on to confrm internal checks but doeswork on switch ive checked the 4 fuses and are ok ive also put on e-croftings kit with no joy ps iust say what an helpful and genuine man roy is he said if the kit didnt work he will work through the problem with me but i dont want to keep bothering him ive borrowed a multimeter and ive got no voltage coming out of eather yellow wires to which the kit attaches yours alan

My light doesn't come on when starting up if it has a fault logged. You could try reading the fault codes and see what that shows up.

You can do it with a DIY fault code reader involving an LED and resistor. There are details in the self help section I think.

Hi Alan

You should have a brief pulse of DC followed by a pulsating signal about 1khz, your meter may read this on the AC range. As far as I know all the ECU's are the same but specific to S1/S2.

Peter.N.

There are some numeric variations from the standard in the tables coded in the 2.5TD's Suspension ECU permanent memory. This actually makes a very small difference at times in the ride performance and either type of XM suspension ECU will work quite happily in a Mk2 XM. An Xantia suspension ECU will have much large numeric variations and should not be used in an XM. All Mk2 suspension ECU's look the same and the base coding of H4 or H5 is just a generic name for that general batch design.
The earliest Mk2 type the H4 had the numeric values stored permanently in a removable EPROM chip so each variant ECU was marked with a detailed code to show which car it was designed for. The later H5 version was manufactured as a single type but with FLASH memory that could be programmed once only for a specific type of car using the Dealers ELIT device. They were supposed to write the car type on the outside of the programmed ECU.

John

hi and thanks il pm garethxm and see if hes breaking the 2.1 estate and try /purchace the ecu if ok yours alan