A scanner would be nice (bg). That car will have actual values and maybe some activation available through a scanner.

But, As I replied I think it can be checked for fault codes by the impulse counting method. There have been many posts on making impulse testers. If you have a scope or voltmeter it can be done using the technique I describe in the DIY article "Evaluating engine controls".

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician