My jeep died while driving. codes PO 700 and PO 562 under voltage. new alternator, cam shaft and crankshaft sensors, new pcm and still cranks no start. same codes. Fuel rail pressurized, battery holds charge, fuses ok. HELP!!
Jeep Liberty 3.7 V6 cranks no start
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Have you checked/bypassed the ASD relay and checked for spark? The ASD relay cuts power to both the injectors and coils, otherwise things seem to work OK.
P0700 indicates the Transmission Control Module (TCM) detected a problem and set a trouble code in memory. You have to read the TCM module for the codes. Those codes may give you a clue. I think some of those codes could prevent the engine from starting. If you have a NAG transmission, the TCM is a separate module. The corporate transmission control software resides in the PCM with some functions in the transmission valve body.
My book says that PO562 is both low and high voltage. It is set when the system voltage is less than a calibrated value for 10 seconds or rises above 15.75 volts
Otherwise check why the PCM and probably TCM are thinking there is a voltage problem. Check for chafed or damaged wires, pushed pins, shorts, bad grounds, corrosion in connectors, rodent damage.... etc. I hear replacement PCMs have more than the usual problems.
Do you have remote start, if so have you tried that?
P0700 indicates the Transmission Control Module (TCM) detected a problem and set a trouble code in memory. You have to read the TCM module for the codes. Those codes may give you a clue. I think some of those codes could prevent the engine from starting. If you have a NAG transmission, the TCM is a separate module. The corporate transmission control software resides in the PCM with some functions in the transmission valve body.
My book says that PO562 is both low and high voltage. It is set when the system voltage is less than a calibrated value for 10 seconds or rises above 15.75 volts
Otherwise check why the PCM and probably TCM are thinking there is a voltage problem. Check for chafed or damaged wires, pushed pins, shorts, bad grounds, corrosion in connectors, rodent damage.... etc. I hear replacement PCMs have more than the usual problems.
Do you have remote start, if so have you tried that?
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what year liberty?
P0700 suggests there are transmission codes, are you using a scanner?
As someone tries to start jeep check for inj pulsing or spark plugs firing.
As helper tries to start jeep spray some , brake clean, carb cleaner or start fluid* into TB - tell us did engine fire and try to start on the spray.
* starting fluid is last on my list - I think its a little to volatile, called boom boom juice for a reason.
PS - if you still have your old PCM keep it.
P0700 suggests there are transmission codes, are you using a scanner?
check and post furl pressure PSI.
As someone tries to start jeep check for inj pulsing or spark plugs firing.
As helper tries to start jeep spray some , brake clean, carb cleaner or start fluid* into TB - tell us did engine fire and try to start on the spray.
* starting fluid is last on my list - I think its a little to volatile, called boom boom juice for a reason.
PS - if you still have your old PCM keep it.
I swapped relay with another- no help.
My book shows 562 as voltage low
563 as voltage high
the PO 700 as transmission control system (MIL request) <— no idea about this, but suggests fix as transmission valve body solenoid replace. There are several codes in my book for solenoids but my scanner has none found. I have a BlueDriver unit that sends readings to the app on my phone.
The PCM and TCM reside together. I recently replaced the computer. Several times I checked as many wires as I could get to and spent a good hour again today unplugging connections and fuses. No bad, damaged wires, coatings or coverings.
There’s no spark to the plugs or injectors from what I can tell. I used a trouble lite and a meter.
My Jeep has no remote start.
2005 Liberty 3.7 V6. I purchased it last July and it ran great until April this year. Engine lite came on while driving and it died within 5 minutes. Using my BlueDriver which sends info to the app on my phone. The reports show no other codes.
There over 55psi in fuel rail. Using starter fluid did nothing… just cranked. Weak or no spark. No ele to spark plugs or injectors. tested with trouble light and meter.
I still have on old pcm. The new one did fix the problem. Why “keep it”?
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700 is the PCM telling us that the TCM software is reporting a fault. Since your scanner can't read the TCM software codes, it looks like no codes are set. Typical consumer scanners only read check engine codes, some also read ABS and AirBag module codes.
Sure sound like the PCM is activating the ASD and shutting down the engine, probably because its seeing a problem. So you won't get spark or fuel injection. So check that battery voltage is getting to on leg of the ASD relay and, if so, instead of swapping the relay, pull it and put a jumper in as a test. If it starts, pull the jumper and troubleshoot why the PCM signal is not getting to the relay coil.
I don't have wiring diagrams handy, but I think there are posts here that discuss it. Perhaps searching for ASD.
They other thing to try is to disconnect the cam sensor and see if it starts. If not, reconnect it and disconnect the crank sensor and see if it starts.
Sure sound like the PCM is activating the ASD and shutting down the engine, probably because its seeing a problem. So you won't get spark or fuel injection. So check that battery voltage is getting to on leg of the ASD relay and, if so, instead of swapping the relay, pull it and put a jumper in as a test. If it starts, pull the jumper and troubleshoot why the PCM signal is not getting to the relay coil.
I don't have wiring diagrams handy, but I think there are posts here that discuss it. Perhaps searching for ASD.
They other thing to try is to disconnect the cam sensor and see if it starts. If not, reconnect it and disconnect the crank sensor and see if it starts.
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13,330 Posts
it does NOT start at all not for @ 2seconds then cut off or when using starting fluid.
ony code is P0700 and P0562?
p0562 - battery OK, did you have to recharge or jump? we will check charging when its running.
Lets see if ASD is closing,
1st remember the 2second time out, if the engine does NOT start in 2seconds the ASD opens meaning no power to injectors, ign etc. That time can make checking a 2 person job.
SO as someone tries to start jeep is there 12v at coil or injector? pick one coil or inj - either wire.
You could jump inj or coil with a test light - it should flash when cranking.
I'm curious WHY did you replace PCM?
how many connectors were on PCM? 3 or 4?
ony code is P0700 and P0562?
p0562 - battery OK, did you have to recharge or jump? we will check charging when its running.
Lets see if ASD is closing,
1st remember the 2second time out, if the engine does NOT start in 2seconds the ASD opens meaning no power to injectors, ign etc. That time can make checking a 2 person job.
SO as someone tries to start jeep is there 12v at coil or injector? pick one coil or inj - either wire.
You could jump inj or coil with a test light - it should flash when cranking.
I'm curious WHY did you replace PCM?
how many connectors were on PCM? 3 or 4?
did not fix the problem. sorry typo
Battery neg post cable was loose, battery died, recharged, checked 12.8V - all good cells
Starting fluid did run the jeep 2 seconds and cut off.
Only 700 and 562 codes.
Replaced the pcm because the Jeep dealer mechanic here and another auto shop both told me the 700 code is TCM faulting. And it in the pcm. There four connections for the pcm
I pulled the plug at the coil and test light did not blink.
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13,330 Posts
1st lets put to rest the P0700 - see attachment - ALL it indicates is that the TCM has requested the CEL on as there are transmission issues.
Checking voltage at coil - see attachment unplug connector when key moved to start or run is there 12v at red wire center of connector.
Then jump the wires 1 to 2 with test light the light should flash as someone cranks eng.
See attachment PDC check f#6 and #24
Checking voltage at coil - see attachment unplug connector when key moved to start or run is there 12v at red wire center of connector.
Then jump the wires 1 to 2 with test light the light should flash as someone cranks eng.
See attachment PDC check f#6 and #24
Attachments
I do understand the communication with the TCP. I was following the Jeep mechanic’s advice. Thankyou.
there’s no voltage at center red wire of coil connector with test light.
I spilled the spark plug connected the coil and turned the engine over. I GOT SPARK!
fuel rail pressure held at 55 psi for 4 hours.
What’s next
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13,330 Posts
engine is cranking - you have spark* next is injector pulsing.
fuse #26 a 15amp in the PDC. Don't just look at fuse probe multimeter or with test light.
Often just looking fails to see the break in fuse.
*We might want to check spark - is there a yellow, blue or white snap to it ?
Confirm spark at several plug wires.
FYI spec for fuel pressure is 58 psi +/- 5 psi so you are good.
fuse #26 a 15amp in the PDC. Don't just look at fuse probe multimeter or with test light.
Often just looking fails to see the break in fuse.
*We might want to check spark - is there a yellow, blue or white snap to it ?
Confirm spark at several plug wires.
FYI spec for fuel pressure is 58 psi +/- 5 psi so you are good.
the spark is orange red. isn’t that weak…low voltage? a blue or white would be stronger?
I’ll check all the spark plugs spark color.
I did check the fuse. it looked good. I’ll replace it tomorrow.
spark plugs are NGK-ZFR 6FGP
all cylinder plugs (6) flash red orange
Battery tests 12.7V
don’t understand ‘rating I am running’
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