Both the engine light and the Check transaxle light came on yesterday

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#1
Make
Mercury
Model
Sable LS
Year
2001
Miles
125000
Engine
Duratec 24 valve DOHC v6 3.0L
2001 Mercury Sable LS 24V 3.0L

Both the engine light and the Check transaxle light came on yesterday. I pulled the code on it and it was a P0705.

So, I figure I would change the Transmission Range (TR) sensor (also called Newtral Position Switch), not that dificult to replace. However, that did not fix the problem.

Each time I put the car in revers it "bucks" (but it has been doing this for 7-8 years), and when I put it in Drive (D) the Check transaxle light starts blinking and it still throws the P0705 code.

I checked the transmission fluid and it looks clean, I could add a little, but the level is still in the hash.

The car still drove well after throwing the code, I have not test driven it after changing the TR sensor.

Any ideas on what to check next.

Regards,
Bill.
 

nickb2

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#2
I think the two situations are unrelated. Since the car has been bucking for 7yrs when going into reverse, and only yesterday the digital TR sensor coded, this will need a different approach.

First, ok you threw a part at the car. It still coded. So you need to get into the wiring.

I say this here way to often. Just cuz you read a code that name a part, you need to go further before just throwing a part at a car and just end up with the same problem.

P0705 specifically states it is a circuit problem. So before thwarting a TR sensor at it, you must ascertain that the wiring is good.

Sometimes, it is only an adjustment that is needed. Or a shifter cable that is binding sending false info to the on board computor, hence setting a false code such as yours.

Here is the FULL trouble shooting chart for your code for your DOHC engine.

See ace 0 pdf.

I know most ppl don't have a breaker box and a high end scanner, but all this can be done with a good old multimeter and some wiring diagrams. in the trouble shoot chart, picturs of the connector views are there and here is a wiring of the range sensor trans set up.

I hope this will give you satisfaction. Then once that code is gone, we will address the bucking in reverse situation you have been having for years.

I am also assuming you have the AX4S trans by your description and writng. Correct me if I am wrong, you can dechiper which one you have by the VIN# and a call to your local dealer.

If by following the chart and wiring I provided, and you have ruled out the wiring after proper check and ruled good, and we know the range sensor is new, only two things can exist, either a bad adjustment/cable/linkage, or a bad PCM.

Screenshot (179).png Screenshot (180).png

;):bat:
 

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#3
nickb2,

Thanks for your comments, very analytical, will get on it right away. Another reason I changed the TR sensor is because I bought one and took an ohm-meter to it and compared my readings to the original one which I had taken out of the car. On the new TR I read (and don't remember if I had them set at Neutral or drive), but I got different readings between pins 1-4 and 1-5. One measured a short between pins 1-5 and the other TR didn't, so I concluded that the old one was bad. By the way I have a Autel Diagtel code reader, don't know if you are familiar with it. I have not used it a lot.

I have a couple of questions, please see attachments. I'm not sure which marker indicates the position, the rectangle natch or the line
 

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nickb2

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#4
I am very familiar with any scanner on the market but I use a autel maxisys elite as my main to go to scanner.

I am not familiar with a Autel Diagtel code reader

Nor does a google search help me on that. I am assuming you just have a "diaglink" Which is just a code reader with VERY LIMITED capabilities.


Now, this is all from memory, but notch should be neutral and all adjustments go from there. Next logical step, is after neutral, notch should align with drive. Follow me so far?

So, first step, take off anything cable related, TR sensor related, and manually MAKE SURE car/trans is in neutral. Once you have ascertained that. Then put back the TR sensor in place. Align notch to "N". Bolt down sensor, then proceed to see if it align with drive when you engage to drive with shift lever. It should line right up. You should see in your dash "D" Don't need a scanner for that.

If all is correct, At this point, don't f with it, as the adjustment point should be done. If you have no joy at this point, suspect binding cable. If cable is free and ok, internal trans component, but I am pretty sure this is not your problem.

On the new TR I read (and don't remember if I had them set at Neutral or drive), but I got different readings between pins 1-4 and 1-5.
As for this comment, there is a resistor inside the TR sensor. If the sensor is f up'ed, You could be getting false reading due to this resistor not ligning up with proper notches inside the range sensor and this sensor is not serviceable. So you were not bad on replacing that sensor, but evidently that is not your problem, so now. Once you get the sensor aligned up right, you should get that code to go away. If not, suspect bad wiring, or bad PCM

Thanks for your comments, very analytical,

As for this comment, I do this all day, every day and it is my bread and butter.

My job is to be analytical, if not, I would not get the paycheck I get every week and have a sweet set up as seen in the open discussion forum here.
 

nickb2

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#5
BTW, thx for taking the time to post pictures, most come here hoping we have a crystal ball, don't take time to answer questions, do not post pics, and most aggravating of all, never come back to post that they actually fixed the problem, even if we helped.

Ego is the main problem, but it sure hurts the site, and us wrenches who spend hours trying to get the info out there for free get the shrug, and no joy to try to convince us that helping others in a free way is appreciated.

The only joy I get from this site is comradeship, and knowing I helped my fellow man from wasting hard earned money on something he/she can fix him/herself with just a nudge in the right direction.

Most often, when some newbie comes along and shrugs off my advice. The site takes care of those arseholes quick enough.

Evidently, you are not of that forge.

BTW, I am french canadian, so sometimes, my french may get in the way of my English. But usually, I am able to get the message across if you follow instructions, which I very well see you are doing. So after we get the TR code done, we will procced to investigate that bucking problem in reverse. I have many options for a guy like you on a dime on the $ if you are willing to hang with me for a while. Will save you money and frustration in the long run, and you will get a huge sense of satisfaction that you got her done yourself with a little bit of help from you new friends.




.
 
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#11
Once line aligns with neutal, when shifting into drive you should see big notch align with big notch symbol on TR sensor. Is that simple enough?
Thanks, really simple. The TR is back on the car, and all the readings I pointed out in the document I just sent were taken with the TR in the car. I did not start the car, I just turned the key to the ON position.
I really appreciate the time you have taken helping me.
 
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#12
Son had that problem in his 2000 Taurus his father-in-law gave to them when they first got married. Just drilled those rivets out, tapped holes for screws, epoxied those in so I could put it back together again.

Contacts were all corroded, polished those to a mirror finish and coated it with GB OX-GARD, also had dimples for contacts, like a pin head, filed those flat for more contact area and increased the spring tension. Think Ford wanted something like 70 bucks for this switch. Was quicker for me to clean it than to drive out there.

This was at a 100K miles, actually put on another 150K and never had problems with it again, reason for dumping it, was a pile of rust.

That car really shocked me compared to what Ford was putting out in the 90's, head gasket problems and some kind of an aluminum clutch in the AT. Major problem was broken stabilizer links, around a foot long as I recall. Also a job to replace the spark plugs, upper intake manifold had to be removed. Other than this, a huge improvement over the 80's and 90's models, surprised Ford didn't go broke, GM sure did.
 
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#13
Well, I may have to do the unthinkable (haven't in over 25 years), take the car to a mechanic, I just do not like working with transmissions. I took new readings yesterday, again, and they seem fine. All the readings I'm getting at TR3A, when I go into each gear are correct, however the car is still throwing the P0705 code and the check transaxle light comes on.

Any other ideas? Worst case scenario, what happens if I continue driving the car?
 
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#14
Still a connectivity problem between the computer and the transmission and sounds like it is erratic, typical of electrical. Another reason why I did not purchase a new neutral safety switch one sitting on the dealer shelves can be just as corroded as the one in your Sable.

Ohmmeters are next to worthless for testing switching contacts, extremely high impedance testing current is in the microampere range. I use a constant current power supply, can go as high as 50 amperes, depending on the switch, on this one 10 amps is sufficient and measure the voltage drop across each contact. Expect it to be far less than 0.1 volt. On only the switch, where the cable plugs into the transmission, On the female side, with a tiny jewelers can crimp those female terminals closed a bit for a tight fit. Can't seem to recall on this car if the transmission control circuit has its own module or if this is part of the ECU, but this is another possibility. Another is the brake switch.

Ha, make the comment don't throw my dirty dishes away either, just clean them and a heck of a lot cheaper than these switches. With dirty contacts or terminals, can also have an arc contact that is really erratic.

Son laid out 110 bucks for a new ABS sensor, looked at it, has a connector right by the strut, while the ABS sensor plug terminals looked clean, the socket it plugged into was not, said problem nothing wrong with your old sensor, just dirty terminals, will have problems again.