Questions about m13a auto + VSS in a Sierra.

[derelict_frog]

Hello All, I have a 2002 auto M13A 99% into a suzuki sierra and have come accross a problem and was wondering if any of you fine people could help me out

Trying to drive it forwards currently is as if you are feathering the clutch in a manual, it wont drive up the smallest incline in high range and low range just manages to motor around. If you rev the engine the engine just revs up and moves you forward a bit better it doesn't spin the wheels as it should. It also does not upchange gears under revs or going down hills. Reverse spins the wheels and appears fine.

So i have some to the conclusion that the auto isn't being told how fast it is going to change up and down gears and found a VSS (Vehicle speed sensor) not plugged in and it might require this to be sending the motor a reading to go forwards correctly. It originally comes out of the Jimny transfer case and looks to be some sort of magnet that i assume reads another magnet spinning around inside. But the sierra transfer case obviosuly has nothing like this.

So after some reading on the net i have come across a sensor you can take out of a vitara dash cluster and attach to the sierras speedo and it reads how fast the speedo cable is turning and tells some engines that are used in conversions useful information. Anyone know if this will tell the correct information to the jimny motor?, i imagine it will send some sort of signal but maybe not in the correct ratios.

This is a link some info on the speedo vitara > sierra vss thing:

http://bbs.zuwharrie.com/content/topic,50369.0.html

This will be a cheap/easy test anyway if i can find a suitable vitara dash.


If this will not work i guess we can mount a magnet somewhere on a correct diameter bit of drive shaft similar to diameter of the spinning bit int he Jimny transfer case and get a reading this way. Haven't looked into to the sizes yet as this would be a less preferred way to go. (more ugly and can get caught on stuff underneath the car).


Or i could be diagnosing the engine symptoms wrong and something else could be unplugged/not setup properly. Any ideas? comments would be much appreciated

[greg]

We did this VSS swap on a G13BB + Auto install into a sierra.

Thus far it is working successfully.

I haven't looked at the link - but from memory we pulled the entire speedo section of a Vitara EFI instrument cluster and grafted it into the Sierra instrument cluster. This turned out to be much nicer / easier than trying to pull some little widget off the back of the vit and screwing it onto the sierra one.

If you are unsure about the M13A + Auto compatibility with the vitara EFI VSS, i would suggest looking at the Suzuki Service Manuals for both cars. I found that they were the same in volts and pulse (?) for the G13BB and G16 EFI cars.

best of luck with it.

[joeblow]

you'll find that the vitara in dash vss and the m13 transfer vss are not compatible. if you want to check if that may be your problem work out which is the signal wire from the cam angle sensor and tie the m13 vss into this. they work with the same signals. this is just temporary and will let you know if you are on the right track.

[derelict_frog]

Well thats not really what i wanted to hear But thanks for the angle sensor suggestion will give that a go.

[derelict_frog]

Few results: Need some more help/tips.


BTW Joe hooking up the VSS wire to the crank angle sensor wire (with or without power applied to the vss wire) had no effect.


Ok so when i was trying it before, even with both looms (sierra and jimny from the engine drivers side back in through the window to the computers in the passengers footwell area) in i didn't have the section with the VSS attached. So i put it all back in and attached that today and it actually up and down shifted while motoring around. Its possible to drive up hills now in high range and kicks in much better.

Still a bit of a problem with it changing though. It changes out of the 1st gear quite fast and then struggles in the 2nd for a while and then into 3rd, i have a feeling it should also drop back into 2nd sooner rather than struggling in 3rd if you are on a hill to keep your speed up. Changing it from D to 2 (via the gearstick) on hills works all right. (would be nice to stay in D and it drop to 2nd gear by itself though) But the take off is quite bad and makes it pretty un-drivable in normal traffic. I believe for it to be more drivable it should rev out in each gear more particularly 1st.

It feels like its struggling more than it should so we swapped the 31" mongrels on it to 29" mts, so possibly slightly bigger than standard sierra wheels but quite a downsize. It made it a bit more drivable but not enough.

Any auto jimny drivers care to shed light on how you motor up changes and what it does on hills?


So im hoping that there is something else i can do to make it more drivable. (with out getting 6.x gearing yet and possibly diff gearing, although if it wont get any better than this that's a possibility). I guess the VSS just has to be plugged in (and the loom its attached to turned on, needs power running through it as well, i tracked the wire right back up to the ignition barrel section. We had a magnet we were waving past it and it didn't seem to have any effect while driving, anyone know how it actually reads the speed, a magnet zipping past or teeth on a transfercase cog?.


So some info on how the jimny vss reads from the jimny transfer case would be useful, the manual doesn't really shed any light on this. I will get the jimny auto ratios so if anyone could tell me if it should be this high geared compared to a sierra.


Jimny m13a auto gear ratios information from the manual:

1st - 2.962
2nd - 1.515
3rd - 1.000
4th (over drive) - 0.737 (don't have OD hooked up atm so it can't go into this)

Final gear reduction ratio (differential) - 3.909


Shift position:

D: 1-2-3
2: 1-2
L: 1

I don't believe we can get it in L currently, it seems to be the same as 2 so the rod just needs some adjusting.

The sierra has standard NT diffs and 4.16 transfer case gearing. With 31"s normally but as above 29's still weren't quite right.

Also currently the motor & auto computers are plugged in with full wiring loom.

Thanks in advance for any info

Jarrod

[jtraf]

VSS actually plugged into the side of the transfer case. The gear it read off I think had twenty five teeth but will find the manual to verify exactly. waving a magnet past it will not be enough for it.

I was going to get the handbrake drum machined to the same spec as the jimny gear to read the speed of the car so that the auto would change properly as it needs the speed to shift properly and hold each gear but I did have a rear disk brack setup with handbrake setup.

Will try get pics for you of the gear out of the manual to hopefully clear it up.

James

[derelict_frog]

That would be useful, i have the manual in pdf form and have read it a few times but can't remember it showing of the the transfer case gear cogs at all.