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Hi Amarin,
Thanks for the detailed photos and comments.
The Porsche ECU repair site was good too.
re: Board with Phillips caps (side view)
Did you check EZK C903 ? a rectangular green block "ERO" cap?
It's adjacent to a crystal and likely part of an oscillator circuit.
The coating over the board can be carefully scraped off around the PTH's
so that solder flows to the PCB track when you reflow.
PTH's are a pain where you sit down, the last two I repaired with a jumper
on the instrument cluster flex board, it was the +12V leg to the fuel gauge working and quitting with it's own perverse schedule to give troubleshooters misery.
Look at PTH.JPG upper right
just between D332 / D504 and T322
for a solder joint that looks like it needs attention.
I wonder if the Siemens 30191 voltage regulator mounted on the big heat sink might benefit from new thermal compound?
It looks like it's riveted on to the heatsink.
When I get my ECU out I'll try placing the PCB over a strong light and see if
the photo will highlight the PCB tracks better.
I'd look first at the legs for the RPM signal.
Good closeups blowup great with the PC to help survey the board.
Some handy tips from the Porsche guys to share here:
The LH2.3 ECUs are very easily damaged by voltage spikes and surges. We recommend:
Never try to jump start the car
disconnect the battery earth (ground ) lead and charge the battery first.
Never use a “rapid charger” with the battery ground connected.
Never do welding on the car without disconnecting the battery
AND also disconnecting the 35way connector on the LH2.3 (and the EZK!)
A faulty alternator, which allows the battery voltage to rise above 16v can destroy the ECU.
Never do any electrical work on the car without disconnecting the battery,
if at all possible.
Otherwise at least make sure the ignition is switched off – at your risk!
Flashovers from faulty ignition leads can damage the ECUs
Connecting the battery with reverse polarity is a sure way to toast your ECU's
The Porsche guys calibrate the AMM? Is there some adjustment in Volvo AMMs?
Best regards, Bill
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