Cranks but no start (codes P0688 and P0522)

garagecouple

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Im at a total loss here! Need your help! 05 TJ drove totally normal last week. Parked and then won't fire up today. Turns over and sounds strong but will not fire. Getting code p0688 p0522 ASD relay error codes. Haven't touched anything since last time when it drove fine. Inspected all fuses and they seem good. Cleaned the grounds and seems good. I'm at a loss here. All help is appreciated! Battery seems strong, cranks hard just no start. Thanks for your time!
 

1RAD

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Swap the ASD relay with a known good one (horn relay) and try to start it.
 

1RAD

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Is the ASD momentarily activating when you turn the key to the run position? Can you hear the fuel pump running momentarily?

If so, is the relay activating while you are attempting to start the engine?
 

Chris

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P0522 possible causes:
  • Faulty oil pressure sensor
  • Low oil level, blockage in the oil passage way or use of wrong oil
  • Open or short in the sensor circuit wiring
  • Bad connection, faulty connector in the oil pressure sensor circuit
P0688 possible causes:
  • Damaged or defective ECM relay
  • Damaged, defective, corroded or loose electrical wiring or related connectors
  • Damaged or defective ECM / PCM
If worse comes to worse, you could always have @Wranglerfix test the PCM for you just to rule it out.
 
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garagecouple

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P0522 possible causes:
  • Faulty oil pressure sensor
  • Low oil level, blockage in the oil passage way or use of wrong oil
  • Open or short in the sensor circuit wiring
  • Bad connection, faulty connector in the oil pressure sensor circuit
P0688 possible causes:
  • Damaged or defective ECM relay
  • Damaged, defective, corroded or loose electrical wiring or related connectors
  • Damaged or defective ECM / PCM
If worse comes to worse, you could always have @Wranglerfix test the PCM for you just to rule it out.
Thanks for the info. How would wranglerfix test the pxm?

Thanks so much
 

1RAD

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I will listen for the fuel pump when I crank it over. I don't think it is.
Listening for the relay closing and fuel pump while the key is first turned to run will test and verify the ASD circuit is functioning.

Verifying that the relay is closed during cranking will indicate that both the cam and crank sensors are functioning.

These circuits must function correctly in order for the engine to start.
 
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garagecouple

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Listening for the relay closing and fuel pump while the key is first turned to run will test and verify the ASD circuit is functioning.

Verifying that the relay is closed during cranking will indicate that both the cam and crank sensors are functioning.

These circuits must function correctly in order for the engine to start.
Thank you for taking the time to share that infor.stion. how do I know what it sounds like for the relay to open or close?
 
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garagecouple

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Listening for the relay closing and fuel pump while the key is first turned to run will test and verify the ASD circuit is functioning.

Verifying that the relay is closed during cranking will indicate that both the cam and crank sensors are functioning.

These circuits must function correctly in order for the engine to start.
Do you think getting this repair done is the issue,? https://wranglertjforum.com/threads/sb-25-001-07.1703/

Jeep ran fine after repair. Don't understand how after sitting for 1 week it doesn't start.
 

1RAD

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Thank you for taking the time to share that infor.stion. how do I know what it sounds like for the relay to open or close?
With the hood open you should be able to hear it momentarily “click” on then off approximately 2 seconds later. During the on period you should also hear the fuel pump running.

If you cannot hear it well enough, have a second person put a finger on top of the relay to feel it activating.
 

1RAD

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Do you think getting this repair done is the issue,? https://wranglertjforum.com/threads/sb-25-001-07.1703/

Jeep ran fine after repair. Don't understand how after sitting for 1 week it doesn't start.
How long did it run fine? Was that something you recently had done?

ASD relays, crank sensors commonly fail, it’s quite possible something along those lines failed when you first attempted to start it after sitting.
 
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garagecouple

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With the hood open you should be able to hear it momentarily “click” on then off approximately 2 seconds later. During the on period you should also hear the fuel pump running.

If you cannot hear it well enough, have a second person put a finger on top of the relay to feel it activating.
Got it. I'll check it out and report back. Also, as far as the tab work involving cutting the asd wires, do you think that could be the cause? It worked fine after getting it done.
 

1RAD

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Got it. I'll check it out and report back. Also, as far as the tab work involving cutting the asd wires, do you think that could be the cause? It worked fine after getting it done.
If you just had it done, you may want to verify that everything is still connected.
 
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garagecouple

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If you just had it done, you may want to verify that everything is still connected.
Yeah, everything is still connected as it should be. Assuming it doesn't click and the fuel pump doesn't hum, what do I do next? Thanks so much for your time! Wondering if I should revert the pcm back to original and undo the tsb
 

1RAD

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Yeah, everything is still connected as it should be. Assuming it doesn't click and the fuel pump doesn't hum, what do I do next? Thanks so much for your time! Wondering if I should revert the pcm back to original and undo the tsb
If the ASD circuit does not pass the pre-start activation test you may want to verify the voltages and grounds for the relay, otherwise have the PCM tested like Chris suggested.
 
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garagecouple

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If the ASD circuit does not pass the pre-start activation test you may want to verify the voltages and grounds for the relay, otherwise have the PCM tested like Chris suggested.
Followed your instructions and today checked the relay as I turned ignition switch on. I get a relay click and also hear the fuel pump fire up. When I go to turn the key it just cranks over and doesn't start, throwing p0688 code each time. Where do I go from here? I installed led tail lights a few days ago, is there any chance this is from that?

Thank you!
 

1RAD

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Ok, so the ASD relay circuit has passed the pre-start test, it’s important to verify that the relay is again closing during cranking.
This is important because it will indicate that the cam and crank sensors are functioning.

* During cranking if the PCM does not receive a valid cam or crank sensor signal it will not close the ASD relay. The ASD relay supplies the power to the coil, fuel injectors and O2 sensors.

If the ASD is closing while cranking and you have verified that the correct voltages and grounds are present, the you will need to have the PCM looked at.
 
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garagecouple

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Ok, so the ASD relay circuit has passed the pre-start test, it’s important to verify that the relay is again closing during cranking.
This is important because it will indicate that the cam and crank sensors are functioning.

* During cranking if the PCM does not receive a valid cam or crank sensor signal it will not close the ASD relay. The ASD relay supplies the power to the coil, fuel injectors and O2 sensors.

If the ASD is closing while cranking and you have verified that the correct voltages and grounds are present, the you will need to have the PCM looked at.
Thanks for this, it is extremely helpful. If it is the cam or crank sensor, wouldn't it throw one of those respective codes? Wondering if the led tail lights caused this. Still baffled that it happened after sitting for a week with the previous drive smooth as ever. What if I was on a trip or overlanding or far away from home? Would have left me totally stranded.