Got a guy asking questions that I can't answer, about a 4 speed auto with shifting issues.
98 tracker 1.6 16V, 4 speed auto, 4x4.

Background
Tranny fluid was flushed and filter changed.  It shifted perfectly for a few hundred miles, after the fluid and filter change.  Then it got so it wouldn't shift into 2nd until 4-4500RPM.  Third and 4th shift is fine.

It doesn't shift hard (with a clunk), when it shifts at high RPM.
The tranny doesn't slip.
The tranny fluid is at the proper level.
Kickdown cable was checked for proper adjustment, it is good.

Tranny shop said there was a VSS error code.  Even though the tranny VSS tested good, he replaced it with another used VSS (that also tested good).  Yes, there is a VSS in the tranny, along with the VSS in the speedometer.
After the tranny VSS swap, it shifted normally for the next 4 or 5 times he tried it.  But then it started with the shifting issue again.  He said it would shift correctly (at the correct RPM) probably about 3 out of 10 times.
I am wondering what error code the tranny shop saw.  There is one code for "VSS" and another code for no signal from either VSS.  The "VSS" code doesn't specify which VSS, so I wonder if the tranny shop just assumed that it was the tranny VSS and didn't think of, or maybe didn't know about, the speedo VSS.  It would make sense that if the speedo VSS isn't working right, that could cause a delayed shift, since the TCM would think that the vehicle speed is 0.
I wonder why there are 2 VSS signals for the TCM?  Is one a backup for the other?  Or do both have to be working properly, for the tranny to shift right?

He has tried running some TransX (tranny cleaner/conditioner) through it.  No change.  He then drained the TransX out.  He said when he pulled the tranny drain plug that it did evidently loosen up some gunk in the tranny (which is surprising, since the tranny fluid was just flushed a few hundred miles ago) and the fluid came out pretty dark.  But now with the fluid refilled, it is clean and no visible contaminates in it.

Currently there are no error codes against the engine or transmission (no CEL and no blinking OD light).

He also says the speedo doesn't start working until about 15 MPH or so.  I guess it just stays at 0 until the vehicle speed is up to about 15MPH and then it jumps to 15 and then moves smoothly up from there.  He says the cable is lubed good and turns smoothly inside the cable housing.
Now, I do know the TCM (tranny control module) does use the input of both the tranny VSS and the speedo VSS in its operation.  So I am wondering if somehow the speedo VSS isn't sending a signal out until the vehicle reaches 15MPH or so (since the speedo needle isn't moving until then) and that is affecting the tranny shifting from 1st to 2nd.  That theory makes sense to me, but I can't figure out how the speedo needle is staying stationary (since it is a cable driven speedo and the speedo cable obviously has to be spinning as soon as the vehicle starts moving).  I am wondering if the needle isn't bouncing a little bit from 0-15 (I've seen that before in trackicks and other vehicles), then starts moving smoothly from 15mph on up.
He did also say that he had the instrument cluster out, to remove/replace one of the indicator bulbs and he initially didn't get the speedo cable plugged back in and it wouldn't shift out of first gear at all.  But once he figured out he didn't get the speedo cable plugged back in good (and plugged it back in), it started shifting again (even though it sometimes shifts at 4500RPM).  Hmm, now that I think about it, I need to ask him if he happened to have the speedo cable unplugged before he took it to the tranny shop.  If so, that would explain why there was a VSS error code showing up.

I also know the TCM uses the TPS signal too (possibly for shifting purposes).  So could it be possible that the TPS has a dead spot in it, or is bad, and that is causing the issue?  I don't think it is, because I would think it would affect more than just the 1st to 2nd gear shift, if it was a TPS issue.  And also it should be a consistent shift problem, not an intermittent one.

I also wondered about a shift solenoid issue.  Maybe an intermittent connection?  Or maybe one that is a little flaky in its operation?  Although, from what I have read, a bad shift solenoid won't cause a high RPM shift issue, it will just make the tranny "skip shift" (shift from 1st to 3rd, for example).

I also wondered about an intermittently faulty TCM.  He is supposed to be checking the shifting with the TCM unhooked, to at least narrow it down to a mechanical tranny issue or an electrical issue.  But my money is on something electrical....a bad connection, a bad component, etc.

Anyone else have any thoughts or advice?

IIRC the cable doesnt actually drive the speedo needle, it drives the vehicle speed VSS and that signal is used to drive the gauge.

Also most E-controlled trans controllers compares the the internal VSS and external VSS so it knows what gear it is in.

IIRC the cable doesnt actually drive the speedo needle, it drives the vehicle speed VSS and that signal is used to drive the gauge.

Also most E-controlled trans controllers compares the the internal VSS and external VSS so it knows what gear it is in.

I am pretty sure it is a mechanical direct drive setup.  The cable comes into the back of the speedo right behind the center of the speedo needle.  IIRC, there is like some sort of clock spring in the speedo...maybe to dampen the input or something.
I know if you put a screwdriver into the back of the speedo and spin the screwdriver the needle will go up....so that tells me it is all mechanical and nothing electrical.
Plus, when you back up, the speedo needle doesn't go up, it just stays at 0.  I think the speedo has to be electrical, in order for the speedo to read speed in reverse.

Yea, your thinking of the 99's when they switched to a digital dash.  There is a VSS (Voltage Speed Sensor) in the speedo to help the computer.

Re the speedometer 0-15 jump - the speedometer itself is probably sticking.  The cable is not attached to the needle, but drives it through a magnetic "interface" - there is a disk and a magnet, but I don't remember which attaches to the cable and which to the needle - the needle is probably sticking close to the 0 mark and needs a little more force to get it moving.  The VSS should be driven directly off the cable and should not be affected by the sticking needle.

I can't offer too much advice on the shift problem, however, I believe that transmission is an AisinWarner AW4, which I have seen in other 4x4 applications - a couple of points - there is no VSS (Vehicle Speed Sensor) on the transmission itself, at least not when it's used in a 4x4 application, because the transmission doesn't know what speed the vehicle is doing - on a 4x4 the VSS will either by located on, or driven from the transfer case.  On an AW4 there should be two speed sensors, input & output shaft, the output shaft sensor is probably what your guy is calling the VSS.

Re the speedometer 0-15 jump - the speedometer itself is probably sticking.  The cable is not attached to the needle, but drives it through a magnetic "interface" - there is a disk and a magnet, but I don't remember which attaches to the cable and which to the needle - the needle is probably sticking close to the 0 mark and needs a little more force to get it moving.  The VSS should be driven directly off the cable and should not be affected by the sticking needle.

I can't offer too much advice on the shift problem, however, I believe that transmission is an AisinWarner AW4, which I have seen in other 4x4 applications - a couple of points - there is no VSS (Vehicle Speed Sensor) on the transmission itself, at least not when it's used in a 4x4 application, because the transmission doesn't know what speed the vehicle is doing - on a 4x4 the VSS will either by located on, or driven from the transfer case.  On an AW4 there should be two speed sensors, input & output shaft, the output shaft sensor is probably what your guy is calling the VSS.

You might be right on the magnetic interface for the speedo needle....been awhile since I've had one apart.  I do recall that the VSS is driven directly off the cable.  So that would indicate that the sticking needle is irrelvant to the VSS operation and likely not the cause of the shifting issue.

The FSM says there is a VSS on the tranny (it even refers to it as a "vehicle speed sensor").  It is on the tranny output shaft.  From what I have found, the TCM uses this speed sensor (along with the speedo VSS, for a backup SS) to determine vehicle speed.

The TCM uses the tranny VSS for its primary vehicle speed input (there is also a 4x4 low range input into the TCM, so it can "adjust" vehicle input speed appropriately).  If the tranny VSS fails, then it uses the speedo VSS input for determining vehicle speed.

A dry cable will give all sorts of erratic readings and can create a static electrical charge.  just another item to check into.

The tranny has two VSS's an input speed sensor and an output sensor (one on each side of trans.), and on newer vehicles the speed output from the TC has a VSS (output goes to TCM, ECM & speedo) .  As all Suzuki's use Asian Warner transmissions, and most others as well, you can use a speed sensor off other make trans., which are much cheaper at the parts store.  (I am using one off a Toy for my input sensor.)  I did not have high rpm shifts with the bad input sensor, but it did throw a code.

A dry cable will give all sorts of erratic readings and can create a static electrical charge.  just another item to check into.

That has been checked.  The cable is lubed up fine.

The tranny has two VSS's an input speed sensor and an output sensor (one on each side of trans.), and on newer vehicles the speed output from the TC has a VSS (output goes to TCM, ECM & speedo) .  As all Suzuki's use Asian Warner transmissions, and most others as well, you can use a speed sensor off other make trans., which are much cheaper at the parts store.  (I am using one off a Toy for my input sensor.)  I did not have high rpm shifts with the bad input sensor, but it did throw a code.

The more I have checked into this, I don't think the VSSs are causing the high RPM shift issue.  I am almost starting to think it is something internal to the tranny...like a leaky seal or gasket...that is causing the issue.

The tranny has a VSS on the drivers side rear of the tranny.  Where is this second VSS in the tranny?  I have looked through the whole section of the FSM dealing with the auto tranny and it mentions nothing of a second VSS in the tranny.

I believe you are right in thinking it is not the VSS's causing the high RPM shift issue.

My FSM for the 2003 - 3 Speed plus OD, in Electronic Shift Control System Description (block diagram) shows both Input and Output Speed sensors on both H25 & H27 models.  Next pages shows wiring diagrams with both speed sensors and VSS (speedometer), again on both models.  I can find reference to checking the resistance of speed sensors, but nothing else in FSM other than codes.  DTC P0717 Input Turbine Speed Sensor, DTC P0722 Output Turbine Speed Sensor.

(On my 05 5 speed the sensors are left side behind bellhousing, and right side in front of TC adapter, and VSS (speedometer) on tailshaft of TC.)  As both my 03 and 05 FSM's reference both speed sensor's and the 05 references both 4&5 speeds I believe they are there.  If earlier years 4 speeds only have one speed sensor, that is one more item to note when considering information, repairs, swapping, etc.

My 98 FSM shows nothing of an input speed sensor for the tranny.  The only VSS code it talks about is the output speed sensor circuit.

Probably changed in 99 with the next models.  I will try to remember that.  I didn't mean to add confusion to your problem.
Is your Output Speed Sensor code 0722?

Probably changed in 99 with the next models.  I will try to remember that.  I didn't mean to add confusion to your problem.
Is your Output Speed Sensor code 0722?

That's my thought too.
My code is P0720 for the tranny VSS.

1-2 shifting issue fixed.

The guy talked with a tranny tech that is pretty familiar with GM trannys and he said if the VSS in the tranny gets much oil on it, the oil will seep in and around the wire insulation and into the sensor and cause the VSS to work sporadically, even though the VSS will pass the ohm test.  The tech was so sure that the tranny VSS was the issue, that he told the guy that he'd pay for the replacement VSS if it didn't fix the problem.
The guy bought a brand new tranny VSS and installed it on Friday.  The tracker started shifting perfectly with the new VSS and has continued to for the last few days.

The thing I find odd, is that the faulty VSS would only cause shifting issues on the 1-2 shift and no others.  I would have thought a faulty VSS would cause shifting issues with all shifts.

Anyway, bottom line is that a brand new tranny VSS has fixed the high RPM 1-2 shifting issue.