Idle Speed Motor Position Sensor: Testing and Inspection
*** UPDATED BY TSB # 9113003, DATED FEBRUARY 1991There are two different wiring harnesses used on this vehicle. A poor connection at a crimp may be causing Code 15. Refer to the TSB for further information.
Motor Position Sensor (MPS):
Idle Switch / Motor Position Sensor Locations:
To test the Motor Position Sensor, attached to the Idle Speed Control (ISC) servo (mounted on the throttle body), proceed as follows.
Motor Position Sensor Test Hook-up:
Motor Position Sensor Resistance Test:
1. Connect an ohmmeter between terminals 3 and 1 of the motor position sensor connector.
Terminal 3: Sensor power
Terminal 1: Sensor ground
2. Measure the resistance of the terminals.
Standard Value...4-7 Kohm
Motor Position Sensor Powered Test:
3. Attach an ohmmeter between terminals 1 and 2 of the motor position sensor connector.
Terminal 1: Sensor ground
Terminal 2: MPS output
4. Connect a 6V battery between terminals 1 and 2 of the ISC motor connector (to operate the ISC motor) and check to see that resistance of the MPS (step #3 hook-up) changes smoothly when the ISC motor is activated.
Standard Value...Approx. 0.5 Kohm increasing to 4-6 Kohm
5. If the standard value is not achieved, or if the change is not smooth, replace the ISC servo assembly.