P1606

Q : DTC P1606. PCM Relay.

Q1 : CHECK THE PCM CONTROL RELAY
1. Turn the ignition switch to the ON position.

Does the PCM relay make an audible click?

Yes
Goto Q2

No
Goto Q3

Q2 : CHECK FOR POWER SUPPLY FROM THE PCM CONTROL RELAY
1. Measure the voltage between the PCM control relay FH32, pin E05 and GROUND.

Is the voltage less than 10 volts?

Yes
Goto Q3

No
REPAIR the circuit from the PCM control relay to the PCM. CLEAR the DTC. TEST the system for normal operation.

Q3 : CHECK FUSE 9 IN THE ENGINE COMPARTMENT FUSE BOX
1. Check the fuse.

Is the fuse OK?

Yes
Goto Q4

No
Goto Q8

Q4 : CHECK THE POWER SUPPLY TO FUSE 9 IN THE ENGINE COMPARTMENT FUSE BOX
1. Measure the voltage between fuse 9 electrical connector FH32, pin 75 and GROUND.

Is the voltage less than 10 volts?

Yes
Repair the circuit from the battery positive to the engine compartment fuse box. CLEAR the DTC. TEST the system for normal operation.

No
Goto Q5

Q5 : CHECK THE POWER SUPPLY FROM FUSE 9 IN THE ENGINE COMPARTMENT FUSE BOX TO THE PCM CONTROL RELAY
1. Measure the voltage between the PCM control relay electrical connector FH32, pin 9 and GROUND.

Is a the voltage less than 10 volts?

Yes
Repair the circuit from the engine compartment fuse box to the PCM control relay. CLEAR the DTC. TEST the system for normal operation.

No
Install a new PCM control relay. CLEAR the DTC. TEST the system for normal operation.

Q6 : CHECK CONTINUITY OF THE PCM CONTROL RELAY GROUND CIRCUIT
1. Disconnect the PCM electrical connector EN16.
2. Remove the PCM control relay from the engine compartment fuse box.
3. Measure the resistance between the PCM electrical connector PI01, pin 40 and FH02, pin E02 of the engine compartment fuse box.

Is the resistance less than 5 ohms?

Yes
Goto Q7

No
Repair the circuit. For additional information, refer to wiring diagrams. CLEAR the DTC. TEST the system for normal operation.

This circuit includes the power distribution fuse box and the EMS relay and diode.

Q7 : CHECK CONTINUITY OF THE PCM CONTROL RELAY WINDING
1. Measure the resistance of the PCM control relay winding between pins 1 and 2 of the PCM control relay.

Is the resistance less than 60 ohms?

Yes
Install a new PCM control relay. CLEAR the DTC. TEST the system for normal operation.

No
Goto Q9

Q8 : CHECK FUSE 9 OF THE ENGINE COMPARTMENT FUSE BOX FOR A SHORT TO GROUND
1. Measure the resistance between electrical connector FH32 pin 9 of the engine compartment fuse box and GROUND.

Is the resistance less than 10,000 ohms?

Yes
REPAIR short to ground between the engine compartment fuse box and the PCM control relay. CLEAR the DTC. TEST the system for normal operation.

No
Install a new fuse. CLEAR the DTC. TEST the system for normal operation.

Q9 : CHECK THE PCM CONTROL RELAY DIODE
1. Remove the PCM control relay diode from the engine compartment fuse box.
2. Measure the continuity of PCM control relay diode.

Is the resistance less than 5 ohms?

Yes
Possible intermittent fault. Recheck DTCs.

No
Install a new PCM control relay diode. Make sure that the PCM control relay diode is installed correctly. For additional information, refer to the wiring diagrams.CLEAR the DTC. TEST the system for normal operation. If DTC is repeated INSTALL a new PCM.