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HDGENE, ASE Certified Technician
Category: Mazda
Satisfied Customers: 5518
Experience:  Master Auto technican
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Mazda Ed, I have a 2006 Mazda 3 with AT light on, noCodes

Customer Question

Hi Mazda Ed,
I have a 2006 Mazda 3 with AT light on , noCodes can be read, Transmission seems to function normally, except will not work in manual mode, cruise control works , etc....
Submitted: 1 year ago.
Category: Mazda
Customer: replied 1 year ago.
Idid mention that I ran through the connectors on the transmission, used contact cleaner, checked for loose pins, it was out of car for engine swap, changed fluid and filter. So all vehicles fluids are fresh. Levels are correct, checked at operating temperature in park and running.
Expert:  FIX IT MAN replied 1 year ago.

Hello, my name is Bobby. Thank you for the question. Did this come on right after you replaced the engine? Is the check engine light coming on also?

Customer: replied 1 year ago.
No check engine light, later on I did have a check engine light come on, which was a PO 420, I reset it, hasn't come back again. I figured there was something wrong with my code reader because I could not read a code from the AT code, so I went to Advance auto parts and he found where the PO 420 was climbing again but had not coded as of yet, but could not pull a Transmission code or reset The AT, He felt that did not make any sense.
However I did have the AT light, and I pulled the battery and went through the connectors, if you have worked on the Mazda 3, its pretty tight but to best of my ability I went through the trans connectors and used contact cleaner on both side of connectors. AT light stayed off for about 40-50 miles, back again. I have not had the trans doing what a lot of the people with the AT Light on, such as safe mode and only having 3rd gear, down shifting constantly at highway speed, cruise control is rock solid as far as function which I would think would omit the TSS. I have not driven a Mazda 3 with a 5 spd automatic previously, but it seems like it functions normally. Seems a little different than a 4L60E or 700R 4 ?!?
Customer: replied 1 year ago.
I did forget to mention, it does not work when put the shifter in manual mode. I had mentioned that before.
Expert:  FIX IT MAN replied 1 year ago.

Thank you. Is the light flashing or staying on steady?

Customer: replied 1 year ago.
It's on steady.
Customer: replied 1 year ago.
its on steady, getting responded to once a day Between 10P.M. and 1:30 A.M. is not getting me anywhere, I believe my symptoms I have posted are fairly clear, I'm trying to be as clear as I can be.
Expert:  FIX IT MAN replied 1 year ago.

I am sorry. I have been unable to get online during the day. I will opt out and allow someone else to be able to help you more effeciently.

Expert:  HDGENE replied 1 year ago.

Hello, what engine is in this mazda 3? What happened to the engine that it had a failure.The p0420 code is probably a bad catalytic convertor not cleaning properly if the upstream and downstream oxygen sensors are switching at the same rate. Im suspecting this is a 2.3 liter engine being a 5 Speed. FNR5 model. Since the transmission was out, long as there wasnt an issue with the torque convertor I am thinking you may have an issue with the transmission range sensor being out of alignment or the trans shifter cable stretched a little and not allowing the transmission range sensor to register the correct gear range. A dealer style or shop higher end scan tool may need to be used to pull transmission codes and most likely setting a code P0700-P0706 for the trange sensor.

Customer: replied 1 year ago.
What does it take for the range sensor adjustment?
Expert:  HDGENE replied 1 year ago.

You want to align the transmission range sensor with the transmission in neutral. you loosen the bolts to adjust and check cable routing make sure its not kinked or binding up.You perform a resistance check between different pins on the tr sensor:



  1. Remove the battery duct and battery cover. (See BATTERY REMOVAL/INSTALLATION [LF, L3] ).
  2. Disconnect the negative battery cable.
  3. Remove the under cover. CAUTION:
    • Water or foreign material entering the connector can cause a poor connection or corrosion. Be sure not to drop water or foreign material on the connector when disconnecting it.
  4. Remove the clip and disconnect the selector cable.
  5. Rotate the manual shaft to the converter housing side fully, then return two notches to set the N position..
  6. Disconnect the TR switch connector.
  7. Loosen the TR switch mounting bolts.
  8. Measure the resistance between the TR switch terminals B and C.
  9. Adjust the switch to the point as follows.


    750 ohms

  10. Tighten the TR switch mounting bolts.

    Tightening torque

    8-11 N.m {82-112, 71-97 in.lbf}

  11. Move the selector lever to N position.
  12. Verify that the TR switch is aligned with N position.
  13. Connect the TR switch connector.
  14. Install the clip to the selector cable as shown in the figure.


  15. Connect the selector cable to the manual shaft lever as shown in the figure.
  16. Inspect the TR switch operation. (See TRANSAXLE RANGE (TR) SWITCH INSPECTION [FS5A-EL] ).
    • If there is any malfunction, readjust the TR switch.
  17. Install the under cover.
  18. Connect the negative battery cable.
  19. Install the battery duct and battery cover. (See BATTERY REMOVAL/INSTALLATION [LF, L3] ).
Expert:  HDGENE replied 1 year ago.

Hello do you need more help with this concern?

Customer: replied 1 year ago.
I did the procedure of setting the range sensor, used the meter, set the sensor. reassembled the car drove it, code AT again, I went ahead and had ordered the TSS, installed it late yesterday, haven't driven it enough yet to see if the AT re appears. I admit that I bought this car with a blown engine so I have no Idea what the trans condition would've been, the car runs great, but the trans feels like it almost stack shifts1st to 2nd, or almost feels like it slips into 2nd, not a definite firm shift like you would have with a 4L60E. Never owned a Mazda so I am not sure. I do have good set of shift solenoids, I'm tempted to install them. My code reader does not read the drive train codes so I'm shooting at the symptoms more than the problems.
Expert:  HDGENE replied 1 year ago.

Ok, let me know if you need more help.