help ecu jeep liberty 3.7 2007

**guzmancillo** · 17th April, 2017, 12:44 AM

Hello, I need help, I have a problem with the ecu of a jeep liberty 3.7 2007 automatic, which does not activate the relay asd, nor does it start. And check all the wiring and everything is ok and also the relays as well as the ipdm that is ok, the code of failure that I have is the P0688, when connecting the relay with cables direct if the pickup starts, but does not remove the warning light. Fault and follows code P0688.

Has to be an electronic fault within the ECU, and check the voltages of the MPC 5554 and I have 5, 3.3, 1.5 and 2.5v. Which according to the freescale data sheet are the ones that arrive, but fails to communicate the ic MC33888 that the switch has 4 high sides and 8 low sides that are the relay asd and others.

I also noticed that I have no clock pulse from the micro quartz resonator MPC5554. But this is fine, it's as if a part of the MCU logic is not activated.

I can enter the diagnostic by scanner I can start the truck (with jumper cables) but it does not remove the fault codes in dashboard and it does not eliminate the P0688.

**vanos batam** · 17th April, 2017, 01:55 AM

Hello..
Can you reading MPC ??

**guzmancillo** · 17th April, 2017, 01:58 AM

Originally Posted by vanos batam

Hello..
Can you reading MPC ??

YES reader. dump to ktag

**clusters** · 17th April, 2017, 02:13 AM

Checked Fuse 24 15A in the PDC? That is the circuit that feeds power from the ASD to the ECU.

**guzmancillo** · 17th April, 2017, 02:29 AM

Originally Posted by clusters

Checked Fuse 24 15A in the PDC? That is the circuit that feeds power from the ASD to the ECU.

If the fuse 24 is fine, and the B + lines reach the pins of C1: 10 and 29 of ECM OK

**clusters** · 17th April, 2017, 02:37 AM

Sorry, my diagram hard to read, should be Fuse 26. This feeds 12V back to the ECU at 3 different locations from the ASD, not the B+ lines.

I'm sure the ECU uses one of these locations to monitor the ASD output and may be the source of your code.

**clusters** · 17th April, 2017, 02:45 AM

Also you should be aware that the ECU needs a cam signal to activate the ASD. If you jumper the relay it may run without the cam signal but will be harder to start.

**guzmancillo** · 17th April, 2017, 02:48 AM

The fuse 26 is that of the output relay which connects to the positive of the 6 ignition coils and the ECM C1: 38, C3: 19, 28. but only can reach these pins when the asd is activated satisfactorily. This is all ok

**guzmancillo** · 17th April, 2017, 04:02 AM

Originally Posted by clusters

Also you should be aware that the ECU needs a cam signal to activate the ASD. If you jumper the relay it may run without the cam signal but will be harder to start.

The fuse 26 is that of the output relay which connects to the positive of the 6 ignition coils and the ECM C1: 38, C3: 19, 28. but only can reach these pins when the asd is activated satisfactorily. This is all ok

**vanos batam** · 17th April, 2017, 05:04 AM

Originally Posted by guzmancillo

YES reader. dump to ktag

post the dump please,,
your Ktag is orig ??

**guzmancillo** · 17th April, 2017, 05:20 AM

Originally Posted by vanos batam

post the dump please,,
your Ktag is orig ??

Yes, the micro reading is complete and the ktag is a clone but make several complete readings without errors and compare them separately and are correct

**hass42** · 18th April, 2017, 12:56 PM

I agree with Clusters, check erratic cam and crank signals.

Hass42

**guzmancillo** · 18th April, 2017, 06:46 PM

signals CKP and CMP OK,

**vanos batam** · 31st October, 2017, 04:13 AM

I never done reading this ecu..
tried 4 pcs ecu/pcm 3.7 0r 3.8

always got mess " micro protection removal "

**vanos batam** · 31st October, 2017, 04:51 AM

Originally Posted by guzmancillo

Yes, the micro reading is complete and the ktag is a clone but make several complete readings without errors and compare them separately and are correct

MATE!!
do you have a full flash from 3.8 this ecu ?
br