5.
Measure output signal between terminal "8"of MC21(or MC121) harness connector and chassis ground.
a.
Specification :
Ignition "OFF".
Disconnect MC21(or MC121) connector,
Connect Scantool to Data Link Connector(DLC).
Start engine and select "SCOPEMETER FUNCTION"on scantool with accelerating engine.
Measure output signal between terminal "8"of MC21(or MC121) harness connector and chassis ground.
Specification :
Is Tachometer output signal within specifications?
YES
Substitute with a known-good EPS CM and check for proper operation.
If the problem is corrected, replace EPS CM and then go to "Verification of Vehicle Repair" procedure.
NO
Check for contact resistance in connections, open/short to ground in signal circuit between PCM(or ECM) and terminal "8"of MC21(or MC121) harness connector repair as necessary.
If they are all normal, substitute with a known-good PCM(or ECM) and check for proper operation.
If the problem is corrected, replace PCM(or ECM) and then go to "Verification of Vehicle Repair" procedure.
