Ody tour

Hey all, I need the experts for this one so thanks in advance for the help....
06 ody touring auto (obviously)

Keep getting P0717 turbine/main shaft (input) speed sensor circuit - no signal

I replaced the sensor after an initial P0715 (same sensor but instead of "no signal" it means "intermittent signal"). It worked for a month and then started giving me the code again.
I took it to Honda and replaced the sensor this time for close to $300... They took my money and told me that didn't fix the problem and told me that I needed to bring it back so they can disassemble my trans... No thanks!

Anyway, I went through the circuit for the sensor which is 3 wire and find no shorts or opens. I've got 5.2 volts from 2 of the wires (yellow and green & blue and white) and the other is ground...

Here's my question.... What else could be wrong? Have any of you had a similar experience?
I can't find any info about how these sensors work. Is there a magnet inside the trans that it reads which could have fallen off? I doubt the PCM is faulty or I wouldn't get 5.2 volts to the power and signal wires... Any ideas???

94EG8

Usually when you start getting transmission codes like that it means the trans is toast.

Ody tour

I hear you, and if the resource most scarce to me was time, I'de just pay to have it repaired or replaced ...
However....
I have 3 small kids, zero income and no unemployment thanks to the current economy so my scarcest resource at the moment is money. I refuse to (can't) throw a few grand at this to replace a trans that functions properly when it has a signal from this sensor.
The trans was engineered and built by people and can therefore be disassembled and repaired by people for the cost of parts. Since none of the gears or clutches are effed up, I can't see scrapping it (nor can I afford it).
C'mon guys.... There's no boogie man in an automatic trans.... I just need to know more about it and how that sensor works to fix it.....


How exactly does that sensor work? What's the pick-up in the trans and does it break/go bad? the sensor is 3 wire: 1 ground / 1 power / 1 signal... How does the signal work? is it a measure of voltage? Why do the power and signal wire have 5.2 volts from the ECU with the key on? Does the sensor reduce the voltage as the RPMs go up?

94EG8

Normally what happens is the trans itself is bad, usually a slipping clutch pack. The PCM expects the mainshaft to be turning at a certain speed at a certain RPM, throttle position etc. Because the clutch pack is slipping it doesn't give a reading that the PCM expects and it throws a code. 99% of the the time when you see a code like this on a Honda there's nothing wrong with the sensor, the wiring, or the PCM, but rather the trans itself is bad and needs a rebuild or replacement. It's not rocket science to build one (I did one of the infamous '03 TL 5 speed automatics last year for someone after I was talked into it, first and only automatic I ever rebuilt) but it does require some specialized tools and info as well as a clean well lit place to work.

You say the clutches aren't slipping, you might be surprised if you took it apart. The TL trans I just mentioned worked perfectly other than a very occasional missed 3rd to 2nd downshift. When I took it apart the 3rd gear clutch pack was absolutely destroyed, the only thing that was reusable was the outer drum.

I'm sure this wasn't what you wanted to hear, and I feel for your situation (also unemployed, will hopefully be working by the end of the month) but in a nutshell that's what normally happens when you get transmission codes in a Honda.

Ody tour

I could understand this if it was the countershaft throwing the code. The PCM compares main and counter shaft speed inputs and knows what gear its in so the PCM knows the exact ratio or difference in speed the two should be sending. If the clutches were slipping, I would get a countershaft speed sensor code and probably codes for incorrect gear ratios. I only get the input (mainshaft) speed sensor code.

That said, you might be on to something if the PCM compares a crank position sensor in the engine to the mainshaft speed sensor. The only thing between the two sensors would be the torque converter so it could be telling me there's an issue there. does anyone know if the PCM compares these two to gauge the torque converters' operation? I would think I'd be getting codes for converter lock-up and such. Can anyone speak to this?

It wouldn't be that bad to replace the TC. Just as much work but far less money... I would have to be sure that was it before I pulled the trigger though. Any way to be certain it's the TC and not the trans?

94EG8

When they first start to fail they don't tend to slip much and it's very occasional.

You would never replace one without at least taking the other apart. If the TC is bad there there's also junk floating around in the trans that will cause it to fail eventually and vice versa. When I rebuilt that TL trans I sent the TC to a transmission shop to have it cut open and rebuilt for $200.

Ody tour

True... Although I hate to admit it...

So it's possible to rebuild these trans's given the proper environment. What special tools are required? I know all the clutch packs are available but if I just replace them and the TC, it won't necessarily fix the trans. What else should be replaced while doing the rebuild? Is there anything in particular associated with the input sensor pickup I should pay special attention to (like a wheel or magnet on the mainshaft)? If so, are those parts available?

The code I get is NO signal, not incorrect signal, so I have to assume there is some failure internally to the trans that I should be prepared for. Any input is again appreciated.

94EG8

You can buy every last piece of the trans if you have to. It's best to completely disassemble the trans and clean it thoroughly. I cheated and didn't take the valve body apart, mainly because I could clearly see where the 3rd gear clutch pack failed and it didn't look like the debris spread. On that note, do as I say, not as I do. Replace the internal filter while you're in there, all gaskets, seals O-rings etc. Check for worn bearings. If I were you I'd probably buy an aftermarket rebuild kit, it will have most of what you need.

In terms of special tools you'll need the tools to compress the clutch packs so you can disassemble them. You'll need a service manual as well (if you know the guy at the parts/service counter sometimes they'll print you the section you need)

All this said, get the troubleshooting flowchart first for that code and go down through it, but it's a very slim chance there isn't something internally wrong with the trans.

Ody tour

I ran through the flow chart which says this is a wiring issue, not an internal trans issue. I went through every wire of the circuit from the trans to the PCM. I found no visible breaks. With the multimeter I found continuity with each end of each wire indicating no open circuits. I also found no continuity with chassis ground indicating no shorts to ground. The flow chart finally says that if all the wiring checks I stated pass, to replace the sensor. I did that (Honda actually did that) and it still gives me the code and goes right into limp mode after 20 seconds of driving. The flow chart states that if the problem persists, to replace the PCM with a known good one. I assume Honda did this since the service manager told me the next step is to disassemble the trans. That step is not listed on the flow chart... It states that if you still get the code with a known good PCM, to go back and start again with the wire tests, then replace sensor, then PCM again until it's fixed...
I stated before that with the key on I get 5.2 volts on 2 of the 3 wires at the sensor plug. The other wire is ground. Are both of these wires supposed to have 5.2 volts from the PCM, when unplugged from the sensor?

Ody tour

Anybody?
review:
With the key on and the mainshaft speed sensor unplugged, these readings were taken from the plug.
1-The power wire is supposed to (and does) have ~5 volts. The troubleshooting procedure states as much.
2-The ground wire is supposed to (and does) have continuity with ground.

It doesn't tell me if or how much voltage I should get from the other (3rd) wire. I assume this is the signal wire back to the PCM which carries a specific voltage depending upon the speed of the mainshaft. Why do I get 5 volts FROM the PCM on this wire?

The ground wire shares it's ground with the EGR valve position sensor and the ATF temp sensor so it cannot bring any signal to the PCM. The power wire shares power from the PCM between the mainshaft speed sensor and the EGR valve position sensor so it also cannot bring a signal to the PCM.

The only wire that can bring a signal from the mainshaft speed sensor has 5 volts coming from the PCM to the mainshaft speed sensor.
WHY?
Someone must know how this sensor is supposed to work and why the PCM is sending voltage instead of receiving it through the signal wire...
I know it's probably the trans but I need to be able to accurately diagnose it before I spend all that money, even if there's only a small chance it could be something else like a bad PCM or wiring?

NonovUrbizniz

You asked for expert advise, you got it... but you're not listening to it.

You dealer and very senior member of a forum both told you your transmission needs to be torn down and even then it's prob. shot.

The reason that the flow chart is telling you to check all the electric parts is that it's HOPING that's the problem, cheap/simple->most expensive repairs.

Feel free to keep asking but it would appear to me a knowledgeable member already explained exactly what the dealer did.

Get a junkyard trans with a 3mo. warranty. prob get it for cheaper than a rebuild.

Ody tour

Yes, I have gotten the most likely culprit and I CERTAINLY mean no disrespect to anyone here especially when they have 11k posts. That's a lot for even for the most active members of a forum so i assume it's been pretty much the most expert advice I can get from anywhere...
That said, I guess I'm just asking specific questions about how it works to help me get my head around it, why I'm getting the code I'm getting, and how the sensors generally work in this car. It's my first Honda and everything works a little differently. I'm used to working on helicopters and VAG cars. In my experience, if one of the 7 transmissions in a Blackhawk fails, I can diagnose the problem down to a specific fault and know exactly what's "broken". Then I can determine if it's something I can repair or just remove and replace the whole unit.
I guess it's just my inquisitive nature that wants to know exactly how and why things work hence the questions about wiring and sensor, parts availability, and such.
I would still like to know how it works and how the signal gets to the PCM. Even if it won't change the outcome or my course of action. I'm sorry if that made me sound like a douche or worse, sound ungrateful for all the help I've gotten so far from someone who obviously knows what they're talking about.

94EG8

There's nothing wrong with being curious or inquisitive.

IIRC those speed sensors work in a similar fashion to an ABS sensor. I believe they have a magnetic pickup and they read off a tone ring.

In terms of electronics, and electrical connections, Honda is very good and making stuff that lasts with very few intermittent failures. What they weren't so good at was making automatic transmissions. I'm not sure if you've ever opened a domestic transmission before (or even most other jap transmissions) but Hondas look more like a manual trans with clutch packs instead of snychronizers. They don't use a planetary arrangement like everything else, so you don't get the torque multiplication (you do get engine braking though) Honda did this to get out of paying for Borg Warner patents. If you have the documentation and special tools available and a clean well lit place to work they aren't that hard to build assuming you're mechanically inclined and follow directions (I'm assuming if you're working Helicopters that's probably a yes)

Ody tour

I had read that about Hondas auto transmissions..., the whole patent infringement dictating their trans design instead of engineering a better method. What a shame.
As far as the sensor goes, I'm familiar with 2 wire wheel speed sensors where a specific voltage is sent to the sensor and the sensor reduces that voltage at a constant rate depending upon how fast the "wheel" it's reading is going. The reduced voltage is sent back to the ecu via the ground wire where the ecu reads the voltage and completes the circuit.
I guess that's what I have in my head as what makes sense. That's why I'm having such a hard time understanding how the signal from a 3 wire sensor gets back to the ecu if the ecu is running 2 power wires to the sensor and a shared ground. I just can't picture the completed circuit where the ecu gets a reading from the sensor.
Well, thanks again for all ur help and i am sorry if my repeated questions was rude or put anyone off. That was never my intention, especially since I'm the one begging for help... Thanks again...

Ody tour

Update:
At this point I'm past the questions and into the trans rebuild. I will not be getting a junk yard trans since its a lot of work to gamble on a 3 month warranty. Also, there have been a few updates to this trans so a junkyard trans is "more"prone to failure than any other option, over and above the fact that it already has use/wear and an unknown service history. A rebuild, I'm told can be done with the "updates", but that requires the rebuilder to know about all of them. It's cheaper to buy the parts than a whole remanufactured unit but the labor bill for remove and replace in the vehicle would be the same. A remanufactured trans would be the most pricey option but you are guaranteed all the aftermarket updated as long as its grime a reputable reman. Co. This option is the most expensive but gives the longest warranty and the best chance for longevity.

Just to clarify how that main shaft speed sensor works, it's like a hall effect sensor... It has a power and a ground wire that supply both + & - to the sensor constantly. The signal wire is supplied with 5 volts constantly from the PCM. The sensor does read a tone ring on the mainshaft and at every revolution, the sensor grounds the signal wire for power to flow. The frequency of this pulsed circuit is what the PCM reads and translates to a speed. A very accurate but fragile way to accomplish this task.
My trans fluid looked perfect when I checked it but there must be microscopic ferrous (magnetic) particles that are clinging to the tone ring because the trans shifts and behaves perfectly fine unless the PCM puts it into limp mode. No slipping or hanging on gears or anything else for that matter.
It's such a shame to have to go through all of this because of the tone ring but I suspect whatever is contaminating it will precipitate a failure in something very shortly.

1-Does anyone else have any info that could persuade me one way or another as far as the 3 options I listed above?
2-has anyone removed the trans from a similar chassis (06) in their driveway and if so, how did you proceed?

94EG8

I helped put one back in a TL, which is somewhat similar after I rebuilt it, I didn't pull it though. Did it in a home garage and it wasn't that bad. I'm pretty sure you have to remove the subframe as well (which isn't hard, it's just heavy and awkward, you'll want a friend to help you.)

Ody tour

I've been told by a local "Honda expert" import repair shop that the subframe must come out so I'm guessing he was correct. He also told me its "impossible" to do one in a driveway and I have a feeling he's just trying to secure my business. He said u have to lift the whole body up over the engine and trans assembly so there's no way to do it without a lift. Im thinking it's possible if you remove the radiator and support and everything else out to the fenders. Then you can just pull the whole assembly out the front. Any opinions on this method or is it not necessary? Im hoping it's, as you say, just heavy and awkward.

94EG8

You don't need a hoist, but it will need to come out through the bottom, so you'll need to find some other way to get it high enough.

george taylor

I have been reseraching this problem since it just showed up on our 07 fit. I was wondering, since I just read about this in another thread, could this code show up if the trans fluid was low. I was just tinkering with the car and checked the level and it seems to be low. We had the trans replaced a few years back when my wife got into a small acident (long story). The trans has appro 70k on it and assume that all the fluid was changed when it was installed.

Ody tour

Nope... A low fluid condition cannot result in this code... The sensor gets a constant signal from the PCM and grounds that signal as the tone ring makes a revolution. The frequency of that grounding is how the PCM knows what speed the mainshaft is turning.
That said, the only components involved with throwing that code are ;
1-the tone ring inside the trans
2- the sensor itself
3- the wireing harness
4- the PCM
If u have this code, one or more of these 4 things is the culprit... Absolutely NOTHING else can trigger or cause it.

Ody tour

Be prepared for a fight on this one too... My ody was out of commission for like 6 months while I argued with the dealership to stop throwing sensors at it at my expense. The whole time my wife was stuck in the house with all 3 kids while severely prego... Thankfully we reached a resolution about 2 weeks before we had our 4th child.
Good luck

george taylor

Thanks. I know the two trans are different, but waht was the culprit with yours?

george taylor

Just talked to my wife about the car. Now I am not sure if the code has cleared itself, do not have a reader that works, but thos is wha she told me. Thear does run fine for a short drive (approx 8 to 15 miles). Then the "D" indicator flashes. Today thecar was in 3rd and when the "D" started to flash it droped back into 2nd and was harder than normal. She was however going up a hill at the time.

Ody tour

Like I said, it was a very bumpy road and the dealership and Honda of America were not a huge help for a while. (I have to give them both credit though as they did everything that could be reasonably expected of them to make it right... Eventually)
I believe it was the PCM all along but Honda isn't convinced... (liability issues)
If you have the service book you can find the procedure to diagnose the fault. It involves
- testing or replacing the sensor with a known good sensor
- testing the wiring harness with a multi meter for faults
- replacing the PCM with a known good PCM...

Here's the issue...
Honda dealers don't have PCMs lying around to test with. They like to just reload the module (group of software that contains the mainshaft speed sensor) on your PCM and run a diag. If the reload takes and passes the diag. (it probably will) they say it's not your PCM.... WRONG...
I finally got Honda of America to get the engineers to approve and send my dealer a known good PCM just to try in my car although it took quite a bit of arguing. That finally fixed the problem.
I had already had 3 speed sensors replaced, the wiring harness, and had to fight tooth and nail to convince them not to take apart my trans...
Any more questions, I'll help in any way I can to save you from the same aggravation...

george taylor

This is going to either make people fall down and laugh or make thm think I am a complete idiot (I am not, I'm an electrican)but here goes. what is the PCM and where is it? If I could find one (juk yard) how can i test it to see if it works or could I find a good friend with a Fit and try thiers?