Test 2 Temperature Switch Open (Codes 53 & 54)

Fig.8 - MCU System Wiring Circuit:

Fig.9 - Electrical Temperature Switch Circuit:

NOTE: Code 53 is for dual temperature switch, circuit 308. Code 54 is for mid-temperature switch, circuit 309.


1 Make sure that engine coolant temperature is between 140-200° F.

2. Disconnect vehicle harness from switch, then connect an ohmmeter across switch terminals, Figs. 8 and 9. If resistance is 10 ohms or less, proceed to next step. If resistance is greater than 10 ohms, replace switch.

3. Disconnect vehicle harness from MCU, then check circuits 60 and 308 (dual), Figs. 8 and 9, 309 (mid) for continuity using an ohmmeter. If resistance is 10 ohms or less, replace MCU. If resistance is greater than 10 ohms, repair circuit.