P1607 what the hell
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Code popped 1607 looked it up said it was a PCM internal shutdown timer rationality too slow, I couldn't even begin to figure out what that whens any body got an idea and how to fix it?
P1607-PCM INTERNAL SHUTDOWN TIMER RATIONALITY TOO SLOW
Theory of Operation
The PCM compares actual shutdown time to a calculated shutdown time value. The calculated shut down time value is based on the amount the ECT, (engine coolant temperature), should drop after a completely warmed up engine is shut down for a minimum of 8 hours. If the difference between actual shutdown time and the calculated shut down time is greater than a maximum value, a one trip failure will set. The shutdown time is measured again after 1 hour of ignition off time following the next engine warm up cycle. The PCM compares the shutdown time to a calculated value. If the difference is greater than a maximum value, the MIL is illuminated and a DTC will set.
Possible Causes
ENGINE COOLING CONDITIONS THAT MAY SET THIS DTC
ENGINE COOLANT LEVEL
PCM INTERNAL TIMER
Theory of Operation
The PCM compares actual shutdown time to a calculated shutdown time value. The calculated shut down time value is based on the amount the ECT, (engine coolant temperature), should drop after a completely warmed up engine is shut down for a minimum of 8 hours. If the difference between actual shutdown time and the calculated shut down time is greater than a maximum value, a one trip failure will set. The shutdown time is measured again after 1 hour of ignition off time following the next engine warm up cycle. The PCM compares the shutdown time to a calculated value. If the difference is greater than a maximum value, the MIL is illuminated and a DTC will set.
- When Monitored: With the engine running after a cycle when a complete engine warm up was achieved, the difference between engine coolant temperature and ambient air temperature less than or equal to 10° C (50° F), and battery voltage greater than 10 volts.
- Set Condition: This DTC sets if the engine coolant temp does not drop enough or drops too much during engine off time. This DTC may also set if the controller timer is inaccurate. Two Trip Fault. Three good trips to turn off the MIL.
Possible Causes
ENGINE COOLING CONDITIONS THAT MAY SET THIS DTC
ENGINE COOLANT LEVEL
PCM INTERNAL TIMER
JK Newbie
I just go this code today. Is it safe to drive with the p1607? 
Quote:
It depends on the cause. Have you checked the coolant level?Originally Posted by alpinestar03
I just go this code today. Is it safe to drive with the p1607?
This is what the service manual says to do:
Diagnostic Test
1. ENGINE COOLANT INSPECTION [HR][/HR] NOTE: This DTC will set if the engine cools quicker than it should compared to engine off times. If the customer washed a hot engine with the engine off, a One Trip Failure will set. If the vehicle is parked in a highly ventilated area or has a large fan blowing on it which might cause the engine to cool quicker than expected this DTC may set.
WARNING: Do not remove or loosen the radiator cap with the system hot and under pressure. Serious burns from coolant can occur.
Turn the ignition off.
Allow the engine to cool enough to allow the pressure in the coolant system to drop enough to safely remove the radiator cap.
Check the coolant level and condition.
Is the engine coolant level filled to the proper level?
Yes
No
2. POWERTRAIN CONTROL MODULE (PCM) [HR][/HR]
Turn the ignition on.
With the scan tool under PCM/NGC Data Display, locate the Ignition Off Time value.
While monitoring a stop watch, turn the Ignition off for 10 minutes, watch the stop watch for those 10 minutes, and then turn the Ignition on.
With the scan tool under Data Functions, check the Ignition Off Time value again.
Does the Ignition Time Off value on the scan tool match the actual time you had the Ignition off on the stop watch?
Yes
No
1. ENGINE COOLANT INSPECTION [HR][/HR] NOTE: This DTC will set if the engine cools quicker than it should compared to engine off times. If the customer washed a hot engine with the engine off, a One Trip Failure will set. If the vehicle is parked in a highly ventilated area or has a large fan blowing on it which might cause the engine to cool quicker than expected this DTC may set.
WARNING: Do not remove or loosen the radiator cap with the system hot and under pressure. Serious burns from coolant can occur.
Turn the ignition off.
Allow the engine to cool enough to allow the pressure in the coolant system to drop enough to safely remove the radiator cap.
Check the coolant level and condition.
Is the engine coolant level filled to the proper level?
Yes
- Go To 2
No
- Add the appropriate type and amount of engine coolant.
2. POWERTRAIN CONTROL MODULE (PCM) [HR][/HR]
Turn the ignition on.
With the scan tool under PCM/NGC Data Display, locate the Ignition Off Time value.
While monitoring a stop watch, turn the Ignition off for 10 minutes, watch the stop watch for those 10 minutes, and then turn the Ignition on.
With the scan tool under Data Functions, check the Ignition Off Time value again.
Does the Ignition Time Off value on the scan tool match the actual time you had the Ignition off on the stop watch?
Yes
- The conditions that set the DTC are not active at this time.
No
- Replace and program the Powertrain Control Module per Service Information.
JK Newbie
Quote:
This is what the service manual says to do:
Diagnostic Test
1. ENGINE COOLANT INSPECTION [HR][/HR] NOTE: This DTC will set if the engine cools quicker than it should compared to engine off times. If the customer washed a hot engine with the engine off, a One Trip Failure will set. If the vehicle is parked in a highly ventilated area or has a large fan blowing on it which might cause the engine to cool quicker than expected this DTC may set.
WARNING: Do not remove or loosen the radiator cap with the system hot and under pressure. Serious burns from coolant can occur.
Turn the ignition off.
Allow the engine to cool enough to allow the pressure in the coolant system to drop enough to safely remove the radiator cap.
Check the coolant level and condition.
Is the engine coolant level filled to the proper level?
Yes
[*]Go To 2
No
[*]Add the appropriate type and amount of engine coolant.
2. POWERTRAIN CONTROL MODULE (PCM) [HR][/HR]
Turn the ignition on.
With the scan tool under PCM/NGC Data Display, locate the Ignition Off Time value.
While monitoring a stop watch, turn the Ignition off for 10 minutes, watch the stop watch for those 10 minutes, and then turn the Ignition on.
With the scan tool under Data Functions, check the Ignition Off Time value again.
Does the Ignition Time Off value on the scan tool match the actual time you had the Ignition off on the stop watch?
Yes
[*]The conditions that set the DTC are not active at this time.
No
[*]Replace and program the Powertrain Control Module per Service Information.
Originally Posted by ronjenx
It depends on the cause. Have you checked the coolant level?This is what the service manual says to do:
Diagnostic Test
1. ENGINE COOLANT INSPECTION [HR][/HR] NOTE: This DTC will set if the engine cools quicker than it should compared to engine off times. If the customer washed a hot engine with the engine off, a One Trip Failure will set. If the vehicle is parked in a highly ventilated area or has a large fan blowing on it which might cause the engine to cool quicker than expected this DTC may set.
WARNING: Do not remove or loosen the radiator cap with the system hot and under pressure. Serious burns from coolant can occur.
Turn the ignition off.
Allow the engine to cool enough to allow the pressure in the coolant system to drop enough to safely remove the radiator cap.
Check the coolant level and condition.
Is the engine coolant level filled to the proper level?
Yes
[*]Go To 2
No
[*]Add the appropriate type and amount of engine coolant.
2. POWERTRAIN CONTROL MODULE (PCM) [HR][/HR]
Turn the ignition on.
With the scan tool under PCM/NGC Data Display, locate the Ignition Off Time value.
While monitoring a stop watch, turn the Ignition off for 10 minutes, watch the stop watch for those 10 minutes, and then turn the Ignition on.
With the scan tool under Data Functions, check the Ignition Off Time value again.
Does the Ignition Time Off value on the scan tool match the actual time you had the Ignition off on the stop watch?
Yes
[*]The conditions that set the DTC are not active at this time.
No
[*]Replace and program the Powertrain Control Module per Service Information.
Okay I just checked the coolant level and it was fine. However the engine temp gauge is acting up. It will say its at operating temp one minute and then below operating temp the next.
Quote:
A bad thermostat can cause that. A bad temp sensor can, too.Originally Posted by alpinestar03
Okay I just checked the coolant level and it was fine. However the engine temp gauge is acting up. It will say its at operating temp one minute and then below operating temp the next.
JK Newbie
Just got it fixed it was the sensor, thanks!
JK Newbie
Just had the same issue pop up on mine....temperature is holding on the gauge where it is suppose to be so going to replace the temp sensor here shortly. $23 and one in stock at the local store.
