Vehicle Speed Signal Circuit Troubleshooting

Special Tools Required:
Test Harness (  07LAJ-PT3020A)
 



M/T:


Before testing, inspect the No. 4 (10A) and No. 10 (7.5A) fuses in the under-dash fuse/relay box.

1.Disconnect the 3P connector from the  vehicle speed sensor (VSS) (A).

 

2.Connect the test harness only to the engine wire harness.

3.Connect the RED test harness clip (B) to the positive probe of an ohmmeter. Cover the white (C) and green (D) test harness leads with protective tape (E).

4.Check for continuity between the RED test harness clip and body ground.

Is there continuity?


YES - Go to 5.


NO - Repair open in the BLK wire between the  VSS and  G101.n

5.Connect the WHT test harness clip (B) to the positive probe of a voltmeter, and connect the RED test harness clip (C) to the negative probe.

 

6.Turn the ignition switch ON (II).

Is there battery voltage?


YES - Go to 7.


NO - Repair open in the BLK/YEL wire between the  VSS and the under-dash fuse/relay box.n


7.Disconnect the WHT test harness clip (B).

8.Connect the GRN test harness clip (D) to the positive probe of a voltmeter.

 

Is there 5 V or battery voltage?


YES - Go to 9.


NO - Repair short or open in the BLU/WHT[WHT/GRN]wire between the  VSS and the  ECM.n

9. Turn the ignition switch OFF.

10.Connect the other test harness connector (A) to the VSS (B).

 

11.Raise the front of the vehicle, and make sure it is securely supported.

12.Put the vehicle in neutral with the ignition switch ON (II).

13.Slowly rotate one wheel with the other wheel blocked.

Does the voltage pulse from 0 to about 5 V or battery voltage?


YES - Go to 14.


NO - Replace the  VSS.n

14.Disconnect the 22P connector ‘‘A'' from the gauge assembly.

 

15.Touch the voltmeter positive probe to the gauge assembly A4 terminal, and connect the negative prove to body ground.

16.Slowly rotate one wheel with the other wheel blocked.

Does the voltage pulse from 0 to about 5 V or battery voltage?


YES - Replace the speedometer assembly.n


NO - Repair open in the BLU/WHT[WHT/GRN]wire between the  VSS and the speedometer.n

A/T:


Before testing, check the No. 9 (10A) fuse in the under-hood fuse/relay box and the No. 10 (7.5A) fuse in the under-dash fuse/relay box.

1.Start the engine, and check the malfunction indicator lamp (MIL).

Does the MIL come on and stay on?


YES - Troubleshoot the PCM DTC, and recheck.


NO - Go to 2.


2.Check the multiplex control unit DTC.

Is the DTC indicated?


YES - Troubleshoot the DTC, and recheck.n


NO - Inspect the connector and socket terminals of the gauge assembly connectors. If the terminals look OK, substitute a known-good gauge assembly and reset. If the problem is fixed, replace the gauge assembly. If the problem is not fixed, replace the  PCM.n