XU9j4 not firing up and weird error codes (ML4.1)

[davemar 16]

My car was running fine, but the alternator was sounding a bit ropey, so decided to change it as I had a spare one. Now I've got it back together, it doesn't want to fire up.

It's a 205 with the Mi16 XU9J4 engine running the Motronic ML4.1 ECU. It doesn't appear to be generating a signal for the ignition amplifier, so I've got no spark.

I decided to try and use the diagnostics to pull out an error code by using pins 4 and 17. I managed to get it to do a self-test to run the injectors and ISCV which made the right sort of sounds, so the basics are fine.

However, when I try to get it to generate an error code all I get is one flash followed by two flashes, so a "1-2" error code. So this isn't much use, as I think all error codes should contain 4 digits (i.e. 4 lots of flashes rather than 2).

Any ideas why its doing this?

 

When I swapped the alternator over I removed the inlet manifold and disconnected a few connectors to the various devices around that part of the engine. I've checked over several times I've put everything back in the correct place, and can't see any obvious mistakes.

 

[pug_ham 244 3 Cars]

You haven't disturbed the CAS plug by accident have you?

 

That would explain the lack of ignition amp signal & spark if the ecu isn't getting a reading from it.

 

g

[davemar 16]

I'll try and pop my oscilloscope on it to check it's still generating a decent signal. I've checked the connection and it looks secure, but it's not unknown for a contact to get dislodged, or a wire breaking in the housing.

I need to recharge my battery first as I've flattened it by trying to start it too much now!

 

[davemar 16]

Just had a check of the wiring inside the connector housing, and sure enough one of the wires had snapped. So hopefully that's the only cause of the problem. The red wire is also just about to break too.

[pug_ham 244 3 Cars]

That's a good possibility, I'd get some new pins & remake them right into the plug (or get a new plug kit) if you've enough free wire to loose an inch.

 

g

[Ryan 99]

18 hours ago, davemar said:

I decided to try and use the diagnostics to pull out an error code by using pins 4 and 17. I managed to get it to do a self-test to run the injectors and ISCV which made the right sort of sounds, so the basics are fine.

However, when I try to get it to generate an error code all I get is one flash followed by two flashes, so a "1-2" error code. So this isn't much use, as I think all error codes should contain 4 digits (i.e. 4 lots of flashes rather than 2).

Error codes on the ML4.1 are only 2 digits, and the ECU only sends them out one code at a time, so you have to repeat the process of shorting the diagnostic pins to get multiple codes.

 

You should always get 1-2 as the first code as that means "Start of test", then any error codes, then 1-1 for "End of test". If you just get 1-2 and then 1-1 it means there are no codes stored.

 

[davemar 16]

Anyway, finally got round to fixing that connector, and the engine now runs fine.