What other things can cause false computer codes that are unrelated. Have read about the alternator having ripple in the signal that can cause problems with other componets. What else can cause problems like this ? Has anyone else had problems with a "ghost" causing them ? Thanks. *BW*

 

what are the codes what are the issues u are having

 

Battery age and condition, battery connections, ground connections (all over the vehicle) many causes. Condition and code can point to a cure. Codes alone not reliable.

 

Thanks to Tech and Firem. Transmission codes and excellent shop has been back thru it again but after some miles same codes come back. Mostly P0740. Thought is something else is causing the codes. Batt has been changed, extra ground cable from batt to body. Pos cable terminal end is tight. Spedo has been ok for the sensor. Someone said throttle pos sensor may be at fault or alternator ripple are the next things to check out. These two and other stuff can be included in a scan and testing for about $100. Hate to spend more money testing but would like to get to the bottom of the problem with more direction. Have been thankful to have some really good techs to work on it so far. Would very much welcome any other ideas to look for. Thanks. *BW*

 

Personal experience says you have a wiring harness that is grounding out and causing the codes...This is especially true if you have had the typical motor mount issues that are common on the Pacifica...Check the wiring harness behind the drivers side wheel...

Remove the front left wheel (drivers side)
-Remove the wheel well shield (just the front is all that is necessary...fold it back)

-Verify the vehicle ground is still intact (when the motor mount gives there is not enough slack in the ground wire and the wire will pull out of the grounding lug)

-Inspect the wiring harness that is around the transmission that goes to the PCM (when the motor mounts give they can crush and then rest on the harness and wear through the casing and then affect the individual wires...throwing codes...)

 

740 is a torque converter clutch issue not a ground or computer or wire issue.

 

I had 14 exposed wires as a result of the failed motor mounts and the engine resting and wearing on the wires...The codes were all over the place...It was driving me and the shop I was taking it to crazy...And I spent a lot of unnecessary money replacing parts chasing this ghost...Nothing made sense...AND if your read Barbara's initial plea....

"What other things can cause false computer codes that are unrelated."

I certainly will not claim to know what initiates a 0740 code...But it has to have a wired path to the PCM...I fail to see why that, if this wired path is compromised, a false code could not result...

This is a FREE solution...A simple inspection...I'll always start with FREE!!!

 

the 740 is based off of several sensors making a mathematical calculation of the internal clutch failure inside the converter itself U can not have a sensor inside a converter that is always e spinning there is no way to have the wires attached.


P0740-TCC OUT OF RANGE
When Monitored and Set Condition:
P0740-TCC OUT OF RANGE
When Monitored: The Torque Converter Clutch (TCC) is in FEMCC or PEMCC, Transmission
temperature is hot, Engine temperature is greater than 38° C or 100° F,
Transmission Input Speed greater than 1750 RPM, TPS less than 30°.
Set Condition: The TCC is modulated by controlling the duty cycle of the L/R Solenoid
until the difference between the Engine and the Transmission Input Speed RPM or duty
cycle is within a desired range. The DTC is set after the period of 10 seconds and 3
occurrences of either: FEMCC - with slip greater than 100 RPM or PEMCC - duty cycle
greater than 85%.

 

To the lay person, which includes me...This doesn't mean a whole lot...Maybe to someone in your station it does...And we are glad to have folks like you!!!

I will continue to contend...There are still sensors making the "mathematical calculations" and they need a highway (the wires) to get their results to the PCM...If the highway is compromised then a wreck can result...

Let's let Barbara make the final call...I stand by my call to inspect for a compromised wiring harness...Simple and free...No one has offered this as an easy solution...It is merely my contribution (that and $5 will get you a great latte at Starbucks)...She can let us all know...Because there are hundreds of Pacifica owners wondering what they should do next to cost effectively fix and maintain their vehicles...

 

Thanks to Traveller and Tech. Just the information I would expect from a forum and others experiences. We had all the mounts replaced a while after the trans was rebuilt the first time. Yes, the wiring could be damaged because of the loose mounts. We will try soon to have a look-see and report back and findings. Keep up the good work. Thanks. *BW*