Trouble codes P0685 & P0688

LAKEG41

MEMBER
2003 CHRYSLER PT CRUISER
4 CYL
FWD
AUTOMATIC
183,000 MILES

I javing a real problem w/ my 2003 PT Cruiser. It runs and starts fine when cold. Sometimes, not always, the car will not or be hard to start and will have to hold gas pedal down part way. The oil pressure light also stays on when this happens. If I shut it down and re-start the light will go out, so I know it isn't a oil pressure problem. I can't draw any codes from a scan tool but the key method shows 0685 & 0688. I've changed the Temp. Sensor so far but have a real feeling it may be the computer. PLEASE HELP !

2 Replies

LAKEG41

MEMBER
2 POSTS

Forgot to say that the "hard start" or "no start" is when the car is warm !

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Monday, November 29th, 2010 AT 6:26 AM

KHLOW2008

MECHANIC
41,815 POSTS

Here are the diagnostics, hope it is helpful.

DTC P0685: ASD RELAY CONTROL CIRCUIT
NOTE:
In testing procedures Alpha/Numeric character in patientness i.E. (K4)
designates circuit. After each repair procedure has been completed,
reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-5 under VERIFICATION TESTS to ensure system is functioning properly.

Monitored & Set Conditions
Circuit is monitored with ignition on. Battery voltage above 10 volts. DTC will set if an open or shorted condition is detected in the ASD relay control circuit. This is a one trip fault.

Possible Causes
� ASD Operation
� (A14) Fused B+ Circuit
� ASD Relay Resistance
� (K51) ASD Relay Control Circuit Open
� (K51) ASD Relay Control Circuit Short To Ground
� PCM

Testing
1. Ignition on, engine not running. With the DRBIII(R) scan tool, actuate the ASD Relay. Is the ASD relay operating? If yes, see INTERMITTENT CONDITION under SELF-DIAGNOSTIC SYSTEM. If no, go to next step.

2. Turn the ignition off. Remove the ASD relay from the Power Distribution Center (PDC). Ignition on, engine not running. Measure the voltage of the (A14) fused B+ circuits in the PDC. Is the voltage above 11.0 volts? If yes, go to next step. If no, repair the (A14) fused B+ circuit. Check and replace any open fuses.

3. Turn the ignition off. Remove the ASD relay from the PDC. Measure the resistance of the ASD relay between the fused B+ terminal and the ASD relay control terminal. Is the resistance between 60-80 ohms? If yes, go to next step. If no, replace the ASD relay.

CAUTION:Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool (8815) to perform diagnosis.

4. Turn the ignition off. Remove the ASD relay from the PDC. Disconnect the PCM harness connectors. Measure the resistance of the (K51) ASD control circuit from the PDC to the appropriate terminal of Miller Special Tool (8815). Is the resistance below 5.0 ohms? If yes, go to next step. If no, repair the open in the (K51) ASD relay control circuit.

5. Turn the ignition off. Remove the ASD relay from the PDC. Measure the resistance between ground and the (K51) ASD relay control circuit in the PDC. Is the resistance below 5.0 ohms? If yes, repair the short to ground in the (K51) ASD relay control circuit. If no, go to
next step.

6. Before continuing disconnect the PCM harness connectors and check the related wiring terminals for corrosion, damage or terminal push out. Repair as necessary. Pay particular attention to all power and ground circuits. If there are no possible causes remaining, replace
and program the PCM. See PROGRAMMING.

DTC P0688: ASD RELAY SENSE CIRCUIT LOW

Monitored & Set Conditions
Circuit is monitored with ignition key on. Battery voltage greater than 10 volts. DTC will set if no voltage sensed at the PCM when the ASD relay is energized. This is a one trip fault.

Possible Causes

� Verify ASD DTC
� ASD Relay
� (A14) Fused B+ Circuit
� (A142) ASD Relay Output Circuit Open
� (A142) ASD Relay Output Circuit Open
� PCM No Start
� PCM Start

Testing

1. If DTC P0685 Auto Shutdown Relay Control Circuit is set along with this DTC, diagnose DTC P0688: ASD RELAY SENSE CIRCUIT LOW first. With the DRBIII(R) scan tool, erase the DTC. Attempt to start the engine. If the engine will not start, crank the engine for at least 15 seconds. It may be necessary to repeat several times. Does the DTC reset? If yes, go to next step. If no, see INTERMITTENT CONDITION under SELF-DIAGNOSTIC SYSTEM.

2. Attempt to start the engine. Does the engine start. If yes, go to next step. If no, go to step 5.

CAUTION:Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool (8815) to perform diagnosis.

3. Turn the ignition off. Remove the ASD relay from the PDC. Disconnect the PCM harness connectors. Measure the resistance of the (A142) ASD output circuit from the PDC to the appropriate terminal of Miller Special Tool (8815). Is the resistance below 5.0 ohms? If yes, go to next step. If no, repair the open in the (A142) ASD relay output circuit.

4. Before continuing, disconnect the PCM harness connectors and check the related wiring terminals for corrosion, damage or terminal push out. Repair as necessary. Pay particular attention to all power and ground circuits. If there are no possible causes remaining, replace
and program the PCM. See PROGRAMMING.

5. Turn the ignition off. Install a substitute relay in place of the ASD relay. Ignition on, engine not running. With the DRBIII(R) scan tool, erase DTCs. Attempt to start the engine. With the DRBIII(R) scan tool, read DTCs. Does the DTC reset? If yes, go to next step. If no, replace the ASD relay.

6. Turn the ignition off. Remove the ASD relay from the PDC. Measure the voltage of the (A14) fused B+ circuit in the PDC. Is the voltage above 11.0 volts? If yes, go to next step. If no, repair the (A14) fused B+ circuit. Inspect the related fuse and repair as necessary.

7. Turn the ignition off. Remove the ASD relay from the PDC. Disconnect the PCM harness connectors. Measure the resistance of the ASD output circuit from the PDC to the appropriate terminal of Miller Special Tool (8815). Is the resistance below 5.0 ohms? If yes, go to next step. If no, repair the open in the ASD relay output circuit(s).

8. Before continuing, disconnect the PCM harness connectors and check the related wiring terminals for corrosion, damage or terminal push out. Repair as necessary. Pay particular attention to all power and ground circuits. If there are no possible causes remaining, replace and program the PCM.