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AX4N shifting issues


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killermrob83
User

Nov 7, 2014, 1:06 PM

Post #1 of 33 (3911 views)
AX4N shifting issues Sign In

'02 Ford Taurus SES, 3.0L Vulcan (OHV), AX4N transaxle, approximately 140K miles.
The car drove fine one day and the next day it doesn't want to make the shift from 3-4. I can get the trans to make the shift by backing completely out of the throttle around 35mph, but as soon as you attempt to ease back into the throttle it downshifts back to 3rd.
I flushed the fluid and changed the filter around 10-12K miles ago, so I figured by dropping the pan I could look for signs of the thing beginning to devour itself. Found nothing out of the ordinary, just a very thin layer of graphite-like sludge around the magnet.
The gear and asterisk icon is flashing (service trans) and the OBDII system is throwing a code of 0750 (shift solenoid A malfunction). I don't want to deceive myself into thinking this is some simple task, but could it be as straightforward as going in and changing out the shift solenoid?
There is also an ABS light that seems to have come on around the same time (I don't know for sure as this is my brother's car). I do not think that this vehicle uses an
ABS wheel sensor speed input to the TCM for shifting, but not sure. I just figured that it must have it's own speed input because the vehicle is making the 1-2 and 2-3 shifts.
Is there a way that I can check the shift solenoid coil resistance from outside of the trans (10 Pin connector located on top)? Can I power up the analog coils with a 12VDC source to listen for the audible clicking when the coil picks up?
Must also let you know that I do not have any formal transmission testing, but I have been doing mechanical/electronic/electrical work all of my life, so I am not intimidated by tearing into a trans. I also do not have all of the great diagnostic equipment that a trans tech would use. I do not want to go to all of the effort to remove the valve body cover with the trans in the car, complete the replacement of the shift solenoids, then reassemble everything only to still have a problem.
All advice/information that you can provide will be greatly appreciated. Thank you for your time and consideration. Rob


gsferraro
Enthusiast

Nov 7, 2014, 4:11 PM

Post #2 of 33 (3891 views)
Re: AX4N shifting issues Sign In

Rob,
Question, If you clear the 750 code does it come right back. The 750 code is shift sol. A electrical malfunction, im very suprised this trans is even shifting with this code. What i would do is disconnect the top connector and instead of powering the solenoids get a wiring diagram and ohm the shift solenoids. There are a total of 5 solenoids under the side cover, 3 of them are shift solenoids make sure they are all the same ohms. resistance should be around 15 to 30 ohms. What type of a scanner are you using to pull the codes, snap-on? Gary


killermrob83
User

Nov 7, 2014, 5:36 PM

Post #3 of 33 (3886 views)
Re: AX4N shifting issues Sign In

I only have an inexpensive code reader that also does mil status. Not sure if the code has come back because the car is on jack stands at the moment. I have already taken some resistance readings across the analog shift solenoid coils. If the points are correct that I was able to locate on a diagram someone was kind enough to send (supposed to be for an '02), then I should have some good readings. These were taken at the 10 pin connector located on top of the trans.
PIN 2-PIN 1 3.6 ohms
PIN 2-PIN 6 15.6 ohms
PIN 2-PIN 8 16.6 ohms


PIN 1-PIN 6 16.6 ohms
PIN 1-PIN 8 17.6 ohms
PIN 6-PIN 8 37.7 ohms
Unless I am looking at this data incorrectly, it's telling me that the coil (A) associated with PIN 1 is weak. Guess I should have asked this question before, but does shift solenoid A even control the shift from 3-4? I asked this based on your response regarding the trans even shifting at all.
Thanks for your reply............ much appreciated.


gsferraro
Enthusiast

Nov 7, 2014, 7:06 PM

Post #4 of 33 (3877 views)
Re: AX4N shifting issues Sign In

Hello,
I just checked a wiring diagram, looks like pin 2 is power to solenoids, pin 1,6,8 sol. grounds. So if you had only 3.6 ohms between pin 1&2 , then its bad. Pin 7&10 will check epc sol. and pins 7&3 is tcc sol. pins5&9 tft sensor. Im suprised its not in failsafe with a 750 code, because thats a straight up eletrical code, thats when i mentioned that i was suprised it even shifted. failsafe is 2nd gear on this trans. Failsafe is when it only stays in one gear because the computer cuts off eletricity to the solenoids. Gary


killermrob83
User

Nov 7, 2014, 7:36 PM

Post #5 of 33 (3873 views)
Re: AX4N shifting issues Sign In

Thanks so much, Gary. Now you've really got me scratching my head as to whether or not the vehicle is shifting from 1-2. This is my brother's car and I only drove it once. I was pretty sure that it shifted from 1-2 (not so sure now). Will be getting some additional readings for the other solenoids and the temp sensor tomorrow, take it off of the jack stands, and drive it again to see if the code reappears (I had previously cleared it) and check the shifting. Will be getting back with my findings. Thank you, again. Rob


killermrob83
User

Nov 9, 2014, 6:48 AM

Post #6 of 33 (3835 views)
Re: AX4N shifting issues Sign In

Got some additional readings.
PIN 7-PIN 10 (EPC) 3.4ohms
PIN 7-PIN 3 (TCC) 12.8 ohms
Could not get a reading other than very high resistance (approx. 100K ohms, but definitely moved off of infinity, so not open) using an analog multi meter (the digital fluke meter that I used for all of the other readings only indicated OL and is auto ranging, so I went to the analog). Was told by an auto tech that I need a scan tool to check the thermistor. Started the vehicle and let it warm up for about 10 minutes, nothing indicated on the dash other than the ABS (and I've come to find out that it's been on for a while). Checked the fluid level to make sure OK.
Took it out for a spin with some peculiar findings:
-made the 1-2 shift at 13mph/1750rpm
-made the 2-3 shift at 22mph/1750rpm, the check engine and service transmission lights both came on, transmission remained in 3rd
- decelerated to the stop sign at the end of the block
Drove it around the neighborhood where I could get the speed up a bit and test the shifting some more. As before, the trans made the first two shifts, then made the 3-4 shift at 32mph/1900 rpm, remained in 4th near 35mph for about a couple hundred yards, then down shifted as if going into safe mode. Drove around several blocks with varying results, sometimes shifting normally and other times not wanting to.
Got back to the house and immediately checked the codes. This time throwing 3:
0743 torque converter circuit electrical
0750 shift solenoid A malfunction
0760 shift solenoid C malfunction


Forgot to mention, also thought I could see a bit of trans fluid in the pinout when I disconnected the harness, so I hit it with electrical contact cleaner and then swabbed it clean and dry with a Q-tip. I also cleaned the connector on the harness end. I did not damage/bend any of the pins.


These findings really have me scratching my head. Remember that I really have no real knowledge of transmissions, but it seems to me as if the TCM (if that's what Ford uses to control the output to the trans) doesn't really know what it's doing. I say that based on the fact that when it's supposed to be in safe mode, it is still making shifts when it shouldn't be. Then, to have these separate issues crop up after basically doing nothing other than drain/refill.


Any thoughts? Also, I have no idea what the resistance readings should be for the EPC and TCC solenoids.


gsferraro
Enthusiast

Nov 9, 2014, 7:13 AM

Post #7 of 33 (3830 views)
Re: AX4N shifting issues Sign In

Hello,
Epc, Tcc sol. resistance is ok. If your getting open readings between pin 2(power for sol.) and pins 1-6-8(sol grounds) there may be a problem with the red wire on pin 2, you may want to do a continunity check or check the wire for voltage(wire comes from fuse 28 at battery junction box, 15 amp fuse) when you clear the codes do they come right back? Also make sure the connector for the trans is down and locked. Are you getting open readings for the solenoids? Gary


killermrob83
User

Nov 9, 2014, 7:44 AM

Post #8 of 33 (3824 views)
Re: AX4N shifting issues Sign In

Not getting any open readings across the analog (A,B,C) solenoids, just the low resistance across the A (PIN 2-PIN 1 3.6 ohms) coil.


There were no codes thrown while the car warmed up for 10 minutes in the drive, and they did not appear until the trans made the shift from 2-3, but the trans stayed in 3rd gear. As I drove away from the stop sign with the service trans icon flashing, the car shifted normally and all the way up to 4th for a bit. The trans harness connector has been pushed down until it clicks/locks into place. No open readings for the solenoids.


Would having this thing scanned with a high end scanner actually tell me anything more?


(This post was edited by killermrob83 on Nov 9, 2014, 7:48 AM)


gsferraro
Enthusiast

Nov 9, 2014, 7:52 AM

Post #9 of 33 (3818 views)
Re: AX4N shifting issues Sign In

solenoids b and c readings are good approx. 15 ohms? Do any of those other codes come back that was listed before.


killermrob83
User

Nov 9, 2014, 7:56 AM

Post #10 of 33 (3815 views)
Re: AX4N shifting issues Sign In

The original code was 0750. After the test drive, the 0750 came back along with the 0743 and 0760.


gsferraro
Enthusiast

Nov 9, 2014, 7:59 AM

Post #11 of 33 (3814 views)
Re: AX4N shifting issues Sign In

B&C sol ohm ok aprox 15 ohms?


killermrob83
User

Nov 9, 2014, 8:03 AM

Post #12 of 33 (3813 views)
Re: AX4N shifting issues Sign In

B was 15.6 C was 16.6


killermrob83
User

Nov 9, 2014, 8:11 AM

Post #13 of 33 (3808 views)
Re: AX4N shifting issues Sign In

Am thinking about clearing the codes and taking it back out for a spin to see what codes reappear.


gsferraro
Enthusiast

Nov 9, 2014, 8:12 AM

Post #14 of 33 (3806 views)
Re: AX4N shifting issues Sign In

I think the first thing to do is address the bad solenoid. That side cover has to come off,(not that easy to do, the frame will have to lowered on one side for room to get the cover off, On an AX4N shift sol A is the one on the top. If the other codes keep coming back 743,760 codes, that may be on the outside of the trans. you may want to check power on those wires that come off the fuse.


killermrob83
User

Nov 9, 2014, 8:22 AM

Post #15 of 33 (3804 views)
Re: AX4N shifting issues Sign In

From what I understand, there is a sub frame cross member that needs to be removed, along with the trans mount (using a jack to support that end of the engine). Does that sound right to you?


I get what you are saying about maybe the problem being external to the trans if the 0743 comes back, since that is for the electrical circuit, but not how the 0760 would be external. Isn't a 0760 the same as a 0750, only for a different solenoid?


killermrob83
User

Nov 9, 2014, 8:28 AM

Post #16 of 33 (3801 views)
Re: AX4N shifting issues Sign In

Would having this thing scanned with a high end scanner actually tell me anything more?


gsferraro
Enthusiast

Nov 9, 2014, 8:33 AM

Post #17 of 33 (3798 views)
Re: AX4N shifting issues Sign In

750 is sol A 760 sol C. 2 different solenoids powered up by the same source, if sol c is within range 15-30 ohms than the solenoid is ok, sol A is 3 ohms thats bad. Thats why i suggested to check for volts at the red wire pin 2 and pin 7. This wire comes from a fuse located in battery junction block, according to the schematic it branches out all over(pin 2 and 7 is the same wire) Im thinking 2 problems. anything done to the car before all this started?


killermrob83
User

Nov 9, 2014, 8:43 AM

Post #18 of 33 (3796 views)
Re: AX4N shifting issues Sign In

Yes, 760 is C solenoid, which tested good with 16.6 ohms, but the computer threw a code for C, identical in description for the code thrown for A, which has a bad reading and needs to be replaced internally.



Replaced the coil pack, plug wires, and plugs. Now that I think about it (all thanks goes to you, Gary), the wires for the #1, 2, and 3 cylinders get routed within close proximity of that harness connector. I wonder if the pin out/harness got damaged changing out the wires. How is the pin out connected/mounted to/in the trans housing? Just from removing/reconnecting the harness connector, it appears to have a very slight amount of give to it, maybe like form a gasket type seating.


(This post was edited by killermrob83 on Nov 9, 2014, 8:51 AM)


gsferraro
Enthusiast

Nov 9, 2014, 8:52 AM

Post #19 of 33 (3786 views)
Re: AX4N shifting issues Sign In

The internal harness is just snapped in place on the inside. The part that sticks out of the trans, you will see it has a tab on it to keep it from being pushed in. The engine harness side has a tab that will lock the two together. there is also a rubber piece inside the engine harness side to keep water out, that sometimes gives me aproblem. once the engine harness is snapped in to the trans harness it shouldnt come out if you pull on it. Check the connections.


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Nov 9, 2014, 8:56 AM

Post #20 of 33 (3785 views)
Re: AX4N shifting issues Sign In

Just a note on a bad/loose connection for products and idea if place allows. Dialectic grease pins with a tooth pick. Smear same just exactly on any rubber to keep water out, wire ties (good ones) can work to hold tight and then outside that brush-in-cap liquid electrical tape is excellent and you can peel that off years later if needed. It's also fuel and oil tolerant. Just thoughts otherwise I'm lostCrazy


T



killermrob83
User

Nov 9, 2014, 8:58 AM

Post #21 of 33 (3783 views)
Re: AX4N shifting issues Sign In

I'll get right on checking into that area. Thanks, Gary. Be back soon if I find anything out of the ordinary.


gsferraro
Enthusiast

Nov 9, 2014, 9:28 AM

Post #22 of 33 (3776 views)
Re: AX4N shifting issues Sign In

okSmile


killermrob83
User

Nov 9, 2014, 11:44 AM

Post #23 of 33 (3767 views)
Re: AX4N shifting issues Sign In

Hearing you say that you're lost doesn't give me a good feeling. Do you think a moderator will jump in here at some point? Here are some more findings.
Did a close up visual on the pin out and harness connector. There were some small cotton fibers (from the Q-tip I used earlier) coated with a light film of probably what used to be dielectric grease and the trans fluid that I cleaned out of the bottom of the pin out. I cleaned the pin out and connector again with contact cleaner and blew them out with compressed air (didn't use any air the last time around).


Checked for voltage at PIN 2 and PIN 7 and got 12 VDC at both locations. Disconnected the battery, pulled the 15 amp fuse out of the battery distribution box (#28), then checked for continuity of the power feed circuit while moving the connector end around (to stress/move the wires around in case of intermittent open/short) and had absolutely no meter deflection away from 0 resistance, telling me that the circuit is good.


Started the car and let it warm up for 10 minutes. No icons illuminated on the dash.
Drove down the block, same as before:
made the 1-2 shift at 13mph/1750rpm
made the 2-3 shift at 22mph/1750rpm
coasted to the stop sign when the service trans light came on (no check engine light)


Drove the car into a 35mph zone, where it shifted normally, even into overdrive at 38mph/not sure of the rpm but guessing around 1500. Turned around to return, where the 1-2 and 2-3 shifts were made, but just as the point was approaching for the next shift the trans downshifted to 2nd. Stopped and restarted, and this time the trans made the shift from 1-2, but would not shift out of 2nd. Another attempt was then made where it shifted normally.


Brought the car back with the service trans icon illuminated, and still no check engine light. I checked for a code and found 1, the 0750 that showed up originally. I firmly believe that that coil is suspect and needs to be replaced, but am wondering what in the world is going on with the operation in this supposed to be safe mode where the trans is not shifting. Are you sure about your description of this transmission's safe mode of operation?


What do you think about me having this thing scanned with a high end scanner like a Snap On job? My brother has a friend that owns one.


(This post was edited by killermrob83 on Nov 9, 2014, 11:47 AM)


gsferraro
Enthusiast

Nov 9, 2014, 12:01 PM

Post #24 of 33 (3762 views)
Re: AX4N shifting issues Sign In

Dont worry, im with you , im not lost, Its probably working sometimes and not other beacuse the solenoid is not totally shorted out, its bad because of the ohms that you are getting. Good job in checking wires and circuits. Thats good that the other codes did not come back. Next step is to get that side cover off to change sol. A, It should be the top solenoid(1st one) this can be verified by dissconnecting it when the cover is off and doing a quick ohms check. Gary


killermrob83
User

Nov 9, 2014, 12:09 PM

Post #25 of 33 (3760 views)
Re: AX4N shifting issues Sign In

Thanks so much for all of the valuable time (yours!) that you have donated toward my cause. I cannot tell you how much I appreciate it.


That last statement you made regarding the A solenoid intermittently casing the trans to operate erratically makes great sense to me.


Time to tackle removing that side cover


Thanks again, Gary! Will follow up when job is done.






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