Need more info on 1111 code

[isham-research.freeserve.co.uk at pop.pol.net.uk]

> Gang, I'm unsure how to proceed on my '89 200.  Pulled
> codes for an intermittent no start condition.  Two
> codes were knock sensor and third was 1111 - ECU
> Defective Memory Circuits.  I hate to replace the ECU
> if that's not the problem. . . ?

Oddly enough I'm looking at a 1111 code from a MAC12 at the moment.

It doesn't actually mean 'memory error' but 'memory CHECKSUM error'.  The
EPROM code in the ECU is checksummed using a very simple algorithm.

However - it appears one of our chipping bretheren does not know this -
or perhaps doesn't know how to calculate the bias byte that guarantees a
good checksum.  All of the ECUs I've found with this problem have
carried chips in sockets with white paper labels as opposed to Audi's
soldered chip with a silver label and dot matrix printing.  All had ids
on them of the form 'L24AM42' - although all have some letters
different, they all begin with 'L'.

I have no audit trail for any of these - the only clue is that one
owner was told verbally that the car had a Lehman chip.

All of the ECUs run perfectly with a stock chip.  I'd suggest pulling
the ECU apart and checking the chip.

--
 Phil Payne
 UK Audi quattro Owners Club
 http://www.isham-research.freeserve.co.uk/quattro
 Phone +44 7785 302803   Fax: +44 7785 309674