01 3.8 GTP w/p1404

Bob et al, do you know if the "learned" EGR minimum position can be affected by a faulty ignition switch? Here's some background:

I have a defective ignition switch (no fan, DIC, heated seat, flashing DRL) and I don't have the time to replaced it. I have a switch installed that by passes the ignition switch so I can have heat and keep my headlights from flashing. I also had the transmission rebuilt last summer and the ignition switch problem started after that repair. Bob, you and I spoke a few months ago about this temporary fix.

Well, one of the first cold mornings here in Atlanta, I got a DTC for the improper temp (I don't remember the code number). The temp gauge barely got off cold. I looked under the hood and both fans were running on high. I disconnected the fans and allowed the engine to warm up. It was cool enough that I didn't "need" the fans as long as I was moving. The temp code reset on it's own after a couple of cycles. I decided to fix the problem and replace the ECT sensor. My understanding of this sensor is that it gives the PCM a coolant temp and the PCM decides if the fans should be on, off, or on-high. It also sends a voltage to the gauge for a visual reading. After replacing the sensor my gauge read what I would guess is normal coolant temp (I believe it was off by about 30 degrees before). Thermostat has been checked.

But my fans still come one when the engine is cold.

My question is this; if I left my rigged ignition switch on, could this confuse the PCM? (temp sensor AND the EGR learned position)? I try to remember to flip the switch but I'm not 100%.

I have a consistant P1404 with each drive cycle. The EGR is clean and moves freely. I have 4.97V at the 5V reference but I'm using a scan tool so I can't change the EGR from 0% to 100%. Any suggestions would be helpful.

Steve

Yes, it is possible the rigged ignition switch may be causing the problems you are having but they could be separate problems so it is hard to say.

The PCM module looks at battery supply and has a sense input where it looks for ignition voltage > 10 volts. So I would check to make sure the battery supply voltage is good to include proper alternator output. Look for around 12.5 volts across the battery positive and negative at ignition off with fully charged battery and at the alternator output with engine running. Around 13.5 - 14.5 volts.

The P1404 DTC is an EGR valve circuit performance error. The PCM module during the diagnostics has detected the EGR valve is stuck open when commanded closed. It looks at the voltage from the EGR pintle position sensor.

The ECT sends a voltage representative of the engine operating temperature. The sensor changes resistance and creates a voltage change. High temp the resistance is low towards zero ohms. Low temp the resistance is high. When you replaced the ECT did you use plumber's tape? The ECT needs a proper ground it gets through the threads. If the fans are running when they should be off the ECT is is putting out resistance that is low or the circuit going back to the PCM module is open. If the reference voltages are good to the sensors and proper back to the PCM module then maybe the PCM module is not seeing that or has an internal problem. When the ECT input to the PCM is incorrect or out if range or missing it will turn the fans on for safety.

When you get a chance and funds permit replacing the ignition switch may help. It is about a 1 hour DIY job and we have the procedure at our new Tips and Maintenance subforum. Good luck.

Bob et al, do you know if the "learned" EGR minimum position can be affected by a faulty ignition switch? Here's some background:

I have a defective ignition switch (no fan, DIC, heated seat, flashing DRL) and I don't have the time to replaced it. I have a switch installed that by passes the ignition switch so I can have heat and keep my headlights from flashing. I also had the transmission rebuilt last summer and the ignition switch problem started after that repair. Bob, you and I spoke a few months ago about this temporary fix.

Well, one of the first cold mornings here in Atlanta, I got a DTC for the improper temp (I don't remember the code number). The temp gauge barely got off cold. I looked under the hood and both fans were running on high. I disconnected the fans and allowed the engine to warm up. It was cool enough that I didn't "need" the fans as long as I was moving. The temp code reset on it's own after a couple of cycles. I decided to fix the problem and replace the ECT sensor. My understanding of this sensor is that it gives the PCM a coolant temp and the PCM decides if the fans should be on, off, or on-high. It also sends a voltage to the gauge for a visual reading. After replacing the sensor my gauge read what I would guess is normal coolant temp (I believe it was off by about 30 degrees before). Thermostat has been checked.

But my fans still come one when the engine is cold.

My question is this; if I left my rigged ignition switch on, could this confuse the PCM? (temp sensor AND the EGR learned position)? I try to remember to flip the switch but I'm not 100%.

I have a consistant P1404 with each drive cycle. The EGR is clean and moves freely. I have 4.97V at the 5V reference but I'm using a scan tool so I can't change the EGR from 0% to 100%. Any suggestions would be helpful.

Steve

Here is a little info on the 1404 code.
***Link Edited Out by Moderator - Leads to copyrighted material***
But as Bnaylor said the switch needs fixed when you can.

:banghead: Hey Bob, I figured out my problems but neglected to tell you about it.

It was a stupid $4.95 thermostat!!!

After I replaced it the temp rose quickly from cold and the SES stayed off after I cleared the codes. I found the Drive Cycle online and haven't had a problem since (actually I still need to replace the ignition switch and now a hub bearing and tie-rod ends, but I passed emissions). Thanks for your help.