need help diagnosing p1404
#11
Senior Member
True Car Nut
Under what operating conditions are you determining there is no signal from the PCM to the EGR? Key on, engine off? Idle? Revving in park? Driving? You may be testing for a signal under conditions where there is not supposed to be a signal. That may be why Mike is trying to get you to focus on whether or not the EGR is the issue.
#12
Under what operating conditions are you determining there is no signal from the PCM to the EGR? Key on, engine off? Idle? Revving in park? Driving? You may be testing for a signal under conditions where there is not supposed to be a signal. That may be why Mike is trying to get you to focus on whether or not the EGR is the issue.
#13
Senior Member
True Car Nut
When the car was built and the computer circuits energized for the first time the computer learned the EGR valve closed position signal from the valve position instrument that is built on top of the valve itself. Over time, when the instrument wears, a slightly different signal is sent to the computer and when it differs enough from the 'Valve Closed Signal', that the computer had learned, the trouble code P1404 is set and the 'Service Engine Soon' light comes on.
Replacing the EGR valve with a new one does not necessarily fix this problem because the 'Valve Closed Signal' between valves is slightly different and it is just pure luck if your new valve would give a 'Valve Closed Signal' close enough to your original valve'* signal not to set the trouble code. This is why the new EGR valve 'Valve Closed Signal' must be re-learned by the computer.
Try this:
1. Disconnect the wire harness from the EGR valve.
2. Turn key ON and erase the trouble code(*) (you need a scanner) from the car'* computer AND TURN KEY OFF IMMEDIATELY WHEN THE SCANNER SAYS CODES HAVE BEEN ERASED. DO NOT TURN KEY ON BEFORE YOU RE-CONNECT EGR WIRE HARNESS.
3. Re-connect EGR wire harness and your problem may be fixed.
Replacing the EGR valve with a new one does not necessarily fix this problem because the 'Valve Closed Signal' between valves is slightly different and it is just pure luck if your new valve would give a 'Valve Closed Signal' close enough to your original valve'* signal not to set the trouble code. This is why the new EGR valve 'Valve Closed Signal' must be re-learned by the computer.
Try this:
1. Disconnect the wire harness from the EGR valve.
2. Turn key ON and erase the trouble code(*) (you need a scanner) from the car'* computer AND TURN KEY OFF IMMEDIATELY WHEN THE SCANNER SAYS CODES HAVE BEEN ERASED. DO NOT TURN KEY ON BEFORE YOU RE-CONNECT EGR WIRE HARNESS.
3. Re-connect EGR wire harness and your problem may be fixed.
#14
When the car was built and the computer circuits energized for the first time the computer learned the EGR valve closed position signal from the valve position instrument that is built on top of the valve itself. Over time, when the instrument wears, a slightly different signal is sent to the computer and when it differs enough from the 'Valve Closed Signal', that the computer had learned, the trouble code P1404 is set and the 'Service Engine Soon' light comes on.
Replacing the EGR valve with a new one does not necessarily fix this problem because the 'Valve Closed Signal' between valves is slightly different and it is just pure luck if your new valve would give a 'Valve Closed Signal' close enough to your original valve'* signal not to set the trouble code. This is why the new EGR valve 'Valve Closed Signal' must be re-learned by the computer.
Try this:
1. Disconnect the wire harness from the EGR valve.
2. Turn key ON and erase the trouble code(*) (you need a scanner) from the car'* computer AND TURN KEY OFF IMMEDIATELY WHEN THE SCANNER SAYS CODES HAVE BEEN ERASED. DO NOT TURN KEY ON BEFORE YOU RE-CONNECT EGR WIRE HARNESS.
3. Re-connect EGR wire harness and your problem may be fixed.
Replacing the EGR valve with a new one does not necessarily fix this problem because the 'Valve Closed Signal' between valves is slightly different and it is just pure luck if your new valve would give a 'Valve Closed Signal' close enough to your original valve'* signal not to set the trouble code. This is why the new EGR valve 'Valve Closed Signal' must be re-learned by the computer.
Try this:
1. Disconnect the wire harness from the EGR valve.
2. Turn key ON and erase the trouble code(*) (you need a scanner) from the car'* computer AND TURN KEY OFF IMMEDIATELY WHEN THE SCANNER SAYS CODES HAVE BEEN ERASED. DO NOT TURN KEY ON BEFORE YOU RE-CONNECT EGR WIRE HARNESS.
3. Re-connect EGR wire harness and your problem may be fixed.
#15
Senior Member
True Car Nut
I've heard of instances where the "EGR trick" doesn't work and the fix was to re-flash the PCM to "learn" the new initial pintle position. I obviously can't be sure that would fix your issue, but it has to be considered. Particularly if you can't find a damaged wire or connector.
#16
I've heard of instances where the "EGR trick" doesn't work and the fix was to re-flash the PCM to "learn" the new initial pintle position. I obviously can't be sure that would fix your issue, but it has to be considered. Particularly if you can't find a damaged wire or connector.
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mikeblue94
Everything Electrical & Electronic
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04-16-2004 01:00 PM