97 Mazda 626 4-Cylinder Automatic: P0708 OBD II Code - Transmission Range Sensor Circuit High Input Diagnosis and Fixes

Here is what the mechanic wrote on the repair sheet. Trans Fluid level (OK), Tested transmission range sensor (OK), Checked tech service bulletins and inspected listed wiring. Checked grounds and transmission connectors (OK), Scan tool shows trans going in and out of drive when KOER but shows OK with KOEO. POSSIBLE BAD PCM I dont know what KOER or KOEO stands for. Also I forgot to tell you that It had also popped a code of P0421 which is the bank one cat effiency low which I believe is the number one O2 sensor which I have not done anything with yet. Total price for them to tell me this $214.43 and it isn't fixed yet that is why I would like a second opinion if possible before I change the PCM.

I'm not familiar with Mazda tranny's per say but I know from first hand experience that the Transmission Range sensors on alot of Ford cars are Junk, so if it's using a Ford part or a ford tranny I'd probably pop for a new range sensor before condemming the pcm. If the pcm can see the signal drop out then I'm less likely to believe the pcm that you're communicating with is bad and more likley that signal it's trying to read is bad, The fact you have an 02 code as well could point to a wiring problem in a common area or it may not be related at all. Some Mazda's had alot of pcm problems because of where they were locatted behind the cup holders but I'd still question that diagnosis alot. KOEO means key on engine off KOER means key on engine running 214 dollars eems alittle low for a pcm, is it new?, used?, aftermarket?, Mazda?

The $214.00 dollars was what I got charged for them to tell me they really didnt know what was wrong. I do understand a new PCm could cost a few hundred depending on where i go to get one. When you mention the Transmission Range sensor, where is it located? Also I believe they tested the transmission range sensor as that is what they put on the service order. How would you test it, does it require a scanner? Last night as long as I kept it below 40 mph it seemed to drive fine with no slippage, but at other times I can feel the slippage at lower speeds. Do you know if the manuals for the trannies have a good trouble shooting guide. I seen a manual for the CDE4 tranny, on line but wasnt sure if it would be of any help to me. Do you know of any manuals you would recommend? Yes this is a ford tranny. I appreciate your help and response. Doug

I found this info while searching a mazda forum and thought i would share. I also like many 626 owners have transmission problems. My newest problem is a code P0708, which means "transmission range sensor circuit high input". I have no clue what that means and was hoping someone could explain this to me. Reply: Oh that actually sounds like (Cant get technical cuz I know only a little from the transmission shop asking the same question), but They told me that the 12 volt sensor that goes to tell the car to shift under heavy load on our cars our s**t so take it to a shop and see if they can fix it its a connection between the throttle and the transmission Reply: Check out this thread which I found in the "How To's" section [on the main page scroll down to find the section]. http://www.mazda626.net/index.php?act=ST&f=28&t=4879 (I copied from the link) The range sensor is adjustable. I get from the picture in the Haynes manual that all it is a potentiomer(variable resistor). You may want to pickup a manual to check it out. I believe you have the CD4E transmission. If that is the case you can check the resistance of the pot in each of the positions. The resistance will vary as measured between pins 1 and 7 depending on which gear position you are in. You may wish just to skip steps 1 thru 4 and go right to step 5 and just check the switch instead of trying to adjust it. Up to you. 1. Place the shift lever in neutral then remove the shift cable from the range sensor arm. 2. Loosen the mounting bolts on the range sensor switch. 3. Rotate the sensor switch to the neutral position. (the neutral position is defined by 2 lines very close together on the sensor. These lines should line up with the metal-keyed shaft that protrudes through the center of the sensor. Yours is probably pretty close to it already since your gears work. 4. Tighten the screws and re-install the shift cable onto the arm. 5. disconnect the connector on the range sensor 6.For the CD4E with your gear shift in "neutral" you should have continuity(0 ohms) between pins 2 and 8 with the connector disconnected. Between pins 1 and 7 you should measure between 660 to 807 ohms. 7.For the CD4E with your gear shift in "reverse" you should have continuity between pins 2 and 8 with the connector disconnected. Between pins 1 and 7 you should measure between 1304 to 1593 ohms. 8.For the CD4E with your gear shift in "Park" you should have continuity between pins 2 and 8 with the connector disconnected. Between pins 1 and 7 you should measure between 3770 to 4607 ohms. 9.For the CD4E with your gear shift in "Drive" Between pins 1 and 7 you should measure between 361 to 442 ohms. Don't worry about the continuity between pins 2 and 8. Reply: I had the exact same code a couple of weeks ago on my 97 2.0L. Took it to the trans shop and it turned out to be a bad wire in the harness that leads to the range sensor. They switched out the wires and fixed it in under an hour. Cost me nothing since the new trans is still under warranty, but I can't see it being very expensive if they did charge me. Reply: Here's a picture of the range sensor if you are wondering what to look for. It's located on top of your tranny underneath the air filter box. Runs $65 at Rock Auto but you can probably find it cheaper. And I would also check what don_mynack said, electrical connections at the Range sensor can cause other issues too such as 'car not even turning over at all' since the park/neutral switch goes through this sensor. Reply: According to my Haynes Manual, on the 4-cyl, adjusting the trans range sensor requires "a special tool". I have no idea what that special tool may be. Has anyone ever done this without the "special tool"? Is this difficult to do, particularly in the case of a replacement? Reply: To answer your question: No I've never needed to replace mine. But since it's just a potentiometer, I get from the process that if you align it per the diagram and your car is able to start in neutral and in park, then you are close to the correct area. At that point you can check the resistance with a meter, the different positions such as park, neutral, drive, 1st, 2nd and reverse to ensure you are in the center of the readings. I would think that the important part would be not to adjust any cable or linkage at the same time as you are replacing the range sensor. Reply: Here's the procedure if you don't have a meter: ADJUSTMENT 1. Place the transaxle selector lever in the neutral position. 2. Loosen the switch mounting bolts. 3. With the switch in the neutral position, insert the proper size pin into the adjustment hole and tighten the attaching screws 4. Remove the screw on the switch body and move the switch so that the screw hole is aligned with the small hole inside of the switch. Check the alignment by inserting a small pin (0.079 in. or 2mm for all models except Millennia, which uses a 0.13 in. or 4mm pin) in the hole. 5. Tighten the mounting bolts and remove the pin. 6. Install the screw to the switch body and tighten. 7. Check the adjustment by trying to start the engine in all gears. It should only start in Park and Neutral. I hope this will help others who may have similar problems: Disclaimer: I found this on the following site http://www.mazda626.net/index.php?showt ... 6&hl=p0708 Here is a picture of the Range sensor (nuetral/park switch) In the middle of the picture you will find a "D" this is where the mark should align when in "Drive" I used a scribe and marked mine in the Park mode prior to removing. Also may i suggest using a digital camera when taking things apart so you have a reference to fall back on. It has worked for me.

If I were you I'd buy a new sensor from the dealer and change it! If your mechanic isn't that familiar enough to know that they are a common failure then he's not that good a tech in my opinion, His invoice is kinda misleading in that it says it's working fine but he can see it drop out on the scanner. no you don't require a scanner to troubleshoot but it is a very long process without one. I know guys at tranny shops that replace it every time they overhaul a ford trans because they are such high failure items. just change it for peace of mind, if still acts up then I'd check the cable condition and adjusttment and the wiring to the sensor!

Thanks Jeff; That is what I will do and let you know how it turns out. Thank you for the advice. Doug

Today i pulled the neutral switch and read it out and it read according to the resistance values. In the process I noticed that the speed sensor is a different part. Jeff is this what you were refering to in the previous post? I dont know exactly how it works with the tranny, but can see that it is all gear driven and translates that out the two pin connector I'm sure to the tranny to let it know when to shift up and down (I could be off track but understand synchros etc) Autozone quoted me $175.00 but also found on line at auto parts giant.com for $112.00. Here is a picture of the speed sensor for any one that might not know what im referring to.

of course the speed sensor and the range sensor are different parts! The part in the link above is the range sensor, I'd recommend a dealer part, likely It will have a Ford part # on it, check both a Mazda dealer and a Ford. Resistance values on a cold part are not as good as one that is electrically loaded and in use, If you're going to remove it replace it! the part with a gear on it is the speed sensor and it's an input for shifting, speedo operation etc! You could replace it as well while your there but it won't likely generate the code you're chasing

Thanks again Jeff, Today while I had the range sensor out I re-read it out and to my surprise I got intermittent readings. If I had it in the drive position it would read good but if I tapped on it it would read open then I would tap it again and it would read good. I went and talked to one of the mechanics at the shop and he told me that the guy who worked on it probaly read it from the computer connection and there for didnt do a tap test on it. I orderd one and it will be in wednesday, I also picked up a Tran cooler and will install tommorrow. I'm crossing my fingers and hope this is the fix. I also got some contact cleaner and sprayed out the connections Last night while searching the web I also read that there is another fix to transmission problems and the link is http://www.drivetrain.com/autotransprob ... rd%20Parts I dont know what the different kits entail but thought I would post for those that want to check it out themselves. Jeff just to clear something up, were you refering to the range sensor as the part the tranny guys change. I'm not to sure where the speed sensor is located, there was another connector near the range sensor that plugged into the tranny. Thanks again for your advice it has been a lot of help.

Jeff Thank you for all your help. I replaced the range sensor and it has been working fine . (Well almost) I still get that mysterious OD light after driving for about 45 - 60 minutes. I can reset it by turning off the car. Will have to research that issue further. I also installed a hayden transmission cooler and mounted it in front of the Air Con condenser coils on the drivers side. Thanks for your help Doug

have it rechecked to see which code is there!

I rechecked and the codes are P1744 (manufactur control transmission) and the P0708 (Trans range sensor circuit high input code again). But it is not going in and out of drive like before just the O/D light after about 30 45 minutes of driving. Also pulled P0441 (evap emission control system purge flow fault) and P0421 (Warm up catalyst below threshold bank 1) I'm thinking the O2 sensor should correct the later two. Any idea whether the solenoid bank inside the tranny could cause the other problem with the O/D light. And do you know is the whole solenoid body replaceable? I should of let that lady smash into me the other day that ran the red light while talking on her cell phone and my problem would be solved thanks

I'd check with a trans shop at this point, they might be able to give you more values from the transmission sensors!