[northrnflyre]

okay so wife has 2012 liberty and was driving and battery light came on and she could hear noise under hood.told her to see if she could make it home as not very far which she did. figured the alternator died. now showing p0688 asd code ,replaced starter, alternator, ignition switch, tested and recharged battery and changed tipm fuse box} still nothing when try to start doesn't turn over .getting power but try to start and dash and radio lights go out like loose ground but checked all. not getting ground to one of the sockets where asd relay goes. anyone have any ideas or experience similar problem. thanks

 

[ColdCase]

Not sure why the lights go out but P0688 is no voltage sensed at the PCM when the ASD is energized or voltage is sensed when the ASD is not energized.

If its the only DTC the problem could be:
(F342) The PCM's ASD CONTROL OUTPUT CIRCUIT SHORTED TO VOLTAGE
(F342) The PCM's ASD CONTROL OUTPUT CIRCUIT OPEN
(F342) The PCM's ASD CONTROL OUTPUT CIRCUIT SHORTED TO GROUND
TOTALLY INTEGRATED POWER MODULE (TIPM)
POWERTRAIN CONTROL MODULE (PCM)

Did a rodent get in there?

The service manual suggests installing a break out box and probing the F342 wires in the cable between the PCM and TIPM for shorts and opens.

You can check the TIPM if you have a full feature scan tool

Ignition on, engine not running
Using the scan tool, in the PCM actuate the ASD
With a 12-volt test light connected to ground, probe the (K51) ASD Control circuit at the C2 TIPM terminal connection

You already replaced the TIPM. If you can't find any damaged or corroded cables, then the PCM may be bad.

A visual check of a ground will not reveal corrosion within the connection. You should try to use an ohm meter, or check for voltage on a spot which should be at a ground potential.

 

[northrnflyre]

Not sure why the lights go out but P0688 is no voltage sensed at the PCM when the ASD is energized or voltage is sensed when the ASD is not energized.

If its the only DTC the problem could be:
(F342) The PCM's ASD CONTROL OUTPUT CIRCUIT SHORTED TO VOLTAGE
(F342) The PCM's ASD CONTROL OUTPUT CIRCUIT OPEN
(F342) The PCM's ASD CONTROL OUTPUT CIRCUIT SHORTED TO GROUND
TOTALLY INTEGRATED POWER MODULE (TIPM)
POWERTRAIN CONTROL MODULE (PCM)

Did a rodent get in there?

The service manual suggests installing a break out box and probing the F342 wires in the cable between the PCM and TIPM for shorts and opens.

You can check the TIPM if you have a full feature scan tool

Ignition on, engine not running
Using the scan tool, in the PCM actuate the ASD
With a 12-volt test light connected to ground, probe the (K51) ASD Control circuit at the C2 TIPM terminal connection

You already replaced the TIPM. If you can't find any damaged or corroded cables, then the PCM may be bad.

A visual check of a ground will not reveal corrosion within the connection. You should try to use an ohm meter, or check for voltage on a spot which should be at a ground potential.



View attachment 4179404

Thanks for the info, I tested the curuits and everything was within the parameters. Appreciate the help, ordered pcm so hopefully that's the issue, not much else to replace. Any recommendations on a decent scanner that will cover most everything without costing a fortune?

 

[ColdCase]

I think AlphaOBD, JScan, AppCar would cover a vintage Liberty. These run on a laptop or phone/ipad. AlphaOBD is a little more complete, but they are mostly the same, just run on different machines and have different licensing.