Autobox, Limp Home Mode again

[Beastlee]

Ok so my auto box has started dropping into limp home mode again. It did it once when Adam was here but then was fine again until today. I floored it in 1st earlier and after that it was shifting very harshly, like having a rear end crash every shift.

When checking it has no leaks at all and the fluid is fine, no untoward sounds either. The diagnostics flash 22 which I believe is the input speed sensor. I gather others have had a similar problem but there's no info on what to do to get to it and/or if it needs to be replaced or can be cleaned.

Can anyone tell me how to get to the sensor please?

[Nick Mann]

IIRC the speed sensor is on the top of the gearbox, more or less under the maf.

Just a clip connection and one (maybe two?) screws holding it in. I have no idea how you would check if it was working, though. I think it works on some kind of proximity thing - its certainly not got the mechanical gear on it that the speedo sender uses.

[Beastlee]

Thanks Nick, I'll have a butchers under there. Unfortunately it's doing it every time I drive the car now and my back is bad enough as it is! Everything else seems fine and I reset the ECU again, it still shows 22 so I gues that sensor has an issue.

[bradc]

do you have an mph converter? Could it be loose wiring or a faulty converter unit?

[Beastlee]

Yes I do, I think it's at the dashboard end, and I have my Profec E-01 wired to the speed sensor signal too, could that be causing the issue do you think? There's no blips on the Profec or on the dash at any time.

[Turbo_Steve]

Could still be the problem: if the sensor voltage return is simply too low then everything may still work, but ECU won't see it (or similar).
Depends what is connected to what, really?

[Nick Mann]

The speedo should not make any difference to the AT ECU.

My converter is fitted to the speedo signal at the gearbox - so all the signals are converted before the ECUs - AYC, Engine, Gearbox etc. My car did not have any isues wih limp home mode until the day the gearbox died.

[Beastlee]

Ok folks I managed to get to the speed sensor, it took aboult half an hour to get to it, take it out and put it all back together. Not a difficult job,just awkward due to the filter box removal. Will add some pics later as I'm in work now.

The torque converter seal was replaced last year and I assume Mitsi will have had to sort the ATF whilst doing it so when I removed it I was particularly concerned by the covering of metal particles at the end. The car isn't due for an ATF change until September but I may need to advance it. My concern is that if the gearbox has a mechanical failure I am totally screwed given my location.

Once I cleaned up the sensor and reconnected/reaffixed everything I took the car up the road again, the harsh changes are still present. My new concern is that when I put it into reverse, whilst at a complete stop, it slams in to gear there. Surely whilst stationary the speed sensor doesn't matter? Or is this the speed of the flywheel? If so I can see why this may have an issue.

OK now for the stream of questions.

Does anyone know the price for a replacement sensor? Does anyone have a spare good one that they would be willing to send for me to test?

When the car goes into limp home mode it really feels like I'm in the middle of a nasty accident and the gearbox makes a very nasty sound, is this normal? I also noticed I can stick it back into tip mode and drop down to second, it still doesn't shift nicely.

I must sort this otherwise I can't get to and from work and, if the gearbox is knackered, the car is a write off for me. Typical after I bought the wheels and only yesterday (before the problem started again) an LC-1.

[Turbo_Steve]

I'm going out on a limb here, as I have no experience with these, but it strikes me that your Quad may be loose or something?

My understanding is that theres an array of sensors / actuators that sit together on top of the box, and make everything happen. If it's loose, the gearbox acts dreadfully, missing gears, slamming about etc, and eventually the ECU gives up and drops to limp mode?

As this sounds "intermittant" it's got to either be something electronic or something loose, surely?

[enyawbrown]

funny enough, I had the very same problem couple weeks ago.......had my transmission totally rebuilt, then when it was put back in the car and we went for a test drive, Neutral light came back on:thinking: So we scanned the car again and the INPUT SPEED SENSOR was going haywire. I bought a new sensor and now everything is A- OK /rally

[Beastlee]

Thanks folks, I guess my only option is to fork out for a replacement sensor.

Steve, it's no longer intermittant, it's now constant.

Enya, do you know the cost of the replacement part? I need to order one ASAP unless a kind member has one they can let me try first.

[Turbo_Steve]

Lee, I'd put up a seperate thread asking to borrow one :)

At least it sounds like it's a relatively easy fix? :(

[peter thomson]

£62 from camskill lee


http://www.camskill.co.uk/products.php?plid=m22b17s1401p6030

[enyawbrown]

Thanks folks, I guess my only option is to fork out for a replacement sensor.

Steve, it's no longer intermittant, it's now constant.

Enya, do you know the cost of the replacement part? I need to order one ASAP unless a kind member has one they can let me try first.


Well, I live in Jamaica, but I paid an equivalent of US$85 for it...think that's about 45 pounds sterling :afro:

[enyawbrown]

£62 from camskill lee


http://www.camskill.co.uk/products.php?plid=m22b17s1401p6030



yup, this is the exact same one :scholar:

[Beastlee]

Fantastic, I can get that tax free and posted to me here! For that money on a common part I may as well buy one. Thanks.

[MarkSanne]

Only just read this topic Lee and I think a new sensor is the best option and not that expensive should it turn out not to be the sensor after all. Other than that, I know a place in NL where they've got a frontclip Legnum with an auto box, should you really need one after all... let me know if/when you need info.

[Beastlee]

I've just gone back to Camskill to order the sensor but I now realise it isn't the same as the one fitted to my car. The part number is different and the shape for the connector is different. Looks like my car will be off the road for quite a while right now.

[MarkSanne]

Lee, post me the partnumber you need and some basic details as where it's located, maybe the frontclip that I mentioned has that sensor still on it, maybe I can find it for you. And maybe a picture of your sensor & connector too just to be 100% sure it's all the same.

[Nutter_John]

may have one lee , will check tomorrow and let you know

[Beastlee]

I have a pic on the camera but no access to a card reader right now. I can read the part no as G4T07171 it looks very similar and may be compatible. Mine has the connector pointing out the rear whereas the one at camskill points up. I'm thinking that's a rubber bung in the connector to keep it clean?

[Beastlee]

Actually I think the only difference is that angle of the connector, I wonder if mine is wrong? I'll look on CAPS later and see if it shows me the correct shape.

From my investigation I think it's silly to have the connector facing upward like that as it's not sealed by the plug and could hold water. When I got the car it regularly spewed coolant over that area and may have casued a problem. As soon as I get a moment to add the pics I'll update the thread.

[Beastlee]

Ok, got a break to work on the laptop.

First pic is the sensor showing the metal filings, the second with the part number :
uploaded/4273/1216988974.jpguploaded/4273/1216989011.jpg

The next two show the engine bay location with the sensor in and out:
uploaded/4273/1216989104.jpguploaded/4273/1216989143.jpg

Thanks for the support folks.

[peter thomson]

Lee going by caps the input speed sensor connector points up the way as the camskill one and the output one points to the side like the one in your pic. Have you taken out the right one. I can't see the other one in the pic but the input one should be nearer the front going by caps

[Beastlee]

Peter, fantastic info, I'll dig around and try to locate it on Sunday. I won't have time between now and then to sort it as we are away at a Bad Taste BEars show tomorrow.
It may yet turn out to be a loose wire or corrosion as the whole area got regularly soaked with the duff rad hose! I've noticed the common factor to both instances of this was that it was immediately after a good thrash in first, it may be that the forces have dislodged something ;)


Next question.....should I be worried about the metal filings coating the tip of the sensor? It was on a small line along the edge as shown, not across the bottom or the opposite side. I'm going to bring the ATF flush forward if I can afford it anyway.

[Beastlee]

OK, I found the input speed sensor /Grrr /pan

Look where the little /Grrr normally is :
uploaded/4273/1217012992.jpg

OK so it's safe to say it's an absolute pig to get to and the swear jar is now full!

Well I stripped it all down and put it back together so if anyone wants a write up I'll do it. It's about an hour and a half to strip and rebuild so could be a Friday afternoon job or any nice weekday.

I cleaned up the sensor that had nothing but ATF on it but I did notice that the location is immediately under the place I had the coolant leak. This pic shows the plastic joiner on the front turbo, its immediately above the sensor :
uploaded/4273/1217013346.jpg
The area of the sensor forms an easy pooling area and I wonder if, despite the unit being sealed, it has had an effect on the sensor.
Anyway, I took it for a run on my little test track, I can try any type of driving on it then drop onto the autobahn for a high speed run.

I managed to have some real fun on the roads near the football ground with high speed cornering and hard acceleration, it shifted better than ever before. The recirc dump valve that Glenn sold me make a lovely chirp!

Unfortunately on the way back to the house, when I was taking it steady, it jumped straight to limp home and, following a restart, it was jumpy again. I assume it's the heat breaking down the internals of the sensor.

Will update again once I get a sensor but for now the car is staying on the drive.

[peter thomson]

Sounds like a fairly positive result and it is just the sensor

[Beastlee]

Well the replacement sensor turned up today. I fitted it in 33degree hot and humid weather and I think the ATF has been watered down by my sweat!

The end result is positive, it shifts like new and on the complete run it didn't miss a beat. Fingers crossed it stays like that!

Thanks for the help everyone.

[martin_y]

Oh wow, fantastic result! To think the car might have been written off for this small part !

[Beastlee]

Have to admit the ECU flashing probably saved my bacon here. Of course I only drove about 3 miles so the real test is Saturday with a 230km drive to Köln and back....oh and the fun drives to and from work each day ;) /yes