2. Powertrain Control Module

Turn the ignition off.

Disconnect the PCM C4 harness connector.

NOTE: Check connectors - Clean/repair as necessary.

Turn the ignition on.

Measure the voltage of the Air Pump Relay Control circuit at the PCM harness connector.

Fig 1: Measuring Voltage Of Air Pump Relay Control Circuit At PCM Harness Connector

Courtesy of DAIMLERCHRYSLER CORP.

Is the voltage above 10 volts?

Yes >> Replace and program the Powertrain Control Module. See ELECTRONIC CONTROL MODULES article.
See POWERTRAIN VERIFICATION TEST - VER 2 .
No >> Go To 3