DTC 15

Fig. 14 Coolant sensor wiring circuit:

Code 15 indicates that the coolant sensor signal received at the ECM is too high. Possible causes of this condition are as follows:
a. An opened coolant sensor.
b. Defective or improperly connected wiring.
c. ECM cannot process code.

To diagnose a Code 15, proceed as follows:
1. Turn ignition on, enter diagnostics and display parameter .0.4. Open circuit reading will be (-)40° to (-)35° C.
2. Disconnect sensor connector and jump harness terminals together.
3. If value of parameter .0.4 is 148-151° C, check for faulty connection of sensor terminals or defective coolant sensor and repair or replace as necessary.
4. If value of parameter .0.4 is 147° C or less, remove the jumper between terminals and jumper circuit No. 410 to ground.
5. If value of parameter .0.4 is 148-151° C, check circuit No. 476-X and repair as necessary.
6. Back probe P-1 (blue) ECM connector pin No. 4 with a jumper to ground.
7. If value of parameter .0.4 is now 148-151° C, check circuit No. 410 for an open and repair as necessary.
8. If value of parameter .0.4 is 147° C or less, check for faulty ECM connector or ECM and replace as necessary.