2000 Mazda Protege DX 1.6L w/air (purchased new) w/42K miles, and FN4A-EL 4 speed auto transmission.

A few months ago at 38,000 miles, the O/D light on my Protege (which I've had since new), started flashing. This would occur perhaps a few times/month after driving the car for about 30 minutes in highway commuter traffic (flashing always ocurred at highway speeds). The flashing comes on at the exact same place on my route...before going up a ramp. This is quite puzzling. The check engine light did not turn on. Autozone's engine scanner came up with trouble code PO771.

From MazdaClub DTC code translation table,

http://www.mazdaclub.net/mz3ws/esic...0219090W05.html

the code translated into "Shift solenoid E stuck off." After the light flashed, when I shut the car off and immediately restarted it, the flashing light would go away. As the flashing would go away, I didn't do anything abou it.
Then 3 weeks ago, the light kept flashing, but this time the check engine light also came on (just staying on...not flashing also). I went to Axiom (wholesale transmission parts distributor), and purchased a trans. filter & gasket for $10, and shift solenoid E for $30 vs $150 at the dealer). Using a clear transmission diagram, (after getting the transmission model number from http://importperformancetransmissio...ion_guide.shtml

http://www.transtec.com/rebuilder_news/2nd_q00r-n.pdf

It states the troubleshooting sequence is as follows: transmission fluid level & condition, if not fixed, then replace transmission, if not fixed, then replace PCM.

I easily dropped the pan myself, changed the transmission filter and solenoid E (along with another transmission flush as the pan was down)...had a complete fluid change done 4,000 miles earlier at Jiffy Lube when the fluid was light brown...but they overfilled by almost a quart.

The lights turned off. But then the O/D light started flashing again on a once/week basis...again...same situation, after 30 minutes of highway driving. Two days ago, the O/D light started flashing, and check engine light came on again. Niether would go out with a restart.

Although I've read many artiles on Ford/Mazdas with flashing OD lights, it seems the Powertrain Control Module (PCM) causes the light to flash when detecting a fault. I had the Mass Airflow sensor replaced under the recall warranty a year ago via my local Mazda dealer. It seems a dirty MAF can casue the OD light to flash.

http://www.fordscorpio.co.uk/odlight.htm

I took the MAF off the car (on top in airflow pipe between airfilter box and injector assembly)...but it was squeaky clean. As the article suggests:

http://www.fordscorpio.co.uk/cleanmaf.htm

I then took the battery and air intake assembly out to see if there were any frayed/cracked wires from when the factory battery acid overflowed (without reason) 4 years ago (I cleaned, applied rust solvent, and repainted the affected parts back then). Everything looked fine.

I've read many Internet articles where Mazda owners have replaced transmissions when this happens but that did not fix flashing light. Aamco recommended replacement...I now know to stay away from Aamco. The transmission shifts fine, and goes into OD 4th gear fine. The only thing I know is that I don't have a transmission problem...I think. But hope it is not a PCM problem. If so, can it be reprogrammed or could it be a wiring harness.

Do you know what the problem may be as I am at a loss and all I get from shops is that I need a new transmission - as I understand most shops are not in the business of actually repairing transmissions? If not, should I buy dealer-level diagnostic software

http://www.fordscorpio.co.uk/obd2a.htm

for $125 from http://www.obd-2.com/

and try to diagnose this elusive problem myself...or do you know the answer?

P.S. While at Axiom, I learned the battery plays a very important part with the PCM. Due to the Dallas heat, I checked my maintenence-free battery a month ago. My 3 yr old Diehard battery needed 1/2 gallon of water... although I don't think this affected things, I thought I'd mention it.

 

i had the same problem. When they checked, I had three code P705, P715, and P302. The 700 codes dealt with the sensor. they had to replace my P neutral switch and input turbine speed sensor on the transmission. It costs me $350 at a local transmission shop.