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Discussion Starter · #1 ·
'97 Sidekick Sport JLX 1.8l, 4-speed automatic transmission sometimes shifts hard from neutral to drive or reverse sitting at idle. It will go most of a day shifting smoothly then start hard shifting. Other days, it shifts hard from the start. It behaves as if the modulator is working intermittently. I understand that it is not a vacuum modulator on this transmission. Is there a way to test the modulator and where is it located?
 

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There is no modulator on the 4 speed tranny, which shifts electronically via the tranny computer. Have you ever checked/replaced the tranny fluid and filter?? Normally, as the shifting is electronically done with solenoids, they will throw a code if they aren't operating properly. Is your check engine or O/D light on with the key on, and off once the car is running?? Some info here on testing the solenoids:
http://www.suzuki-forums.com/suzuki...cker/84969-1997-geo-tracker-4-speed-wont.html
 

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Discussion Starter · #3 ·
Thanks for the reply. I got the car at 101,000 and flushed the tranny. (Pulled the pan, cleaned the screen, replaced the pan, re-filled the fluid, broke the fitting at the radiator, ran it for 20 seconds, replaced the fluid pumped out, repeated twice and it looks pretty clean.) The OD lamp comes on when the key is turned on and goes off after a few seconds. The Check Engine light goes off when the engine starts. The Air Bag warning flashes 7 times and goes off. My scanner shows no stored codes. I'll check the solenoid checking link. Thanks
 

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99 Tracker, 5 door, 2L, 4x4
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A standard OBDII scanner will not read MFG extended codes, (ABS, Air bags. Transmission)...

What RPM do you see when the transmission does its clunk?
Have you checked for failed U-joints or loose transmission/engine mounts?

... Philip
 

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Discussion Starter · #5 ·
I have the OBD Wiz software. Don't know about its ability to read extended codes.

The hard shifts are always at idle when I'm first starting out or reversing direction. RPM does not seem to be a factor since, when it's not misbehaving, it will shift smoothly from park or neutral to drive or reverse even at fast idle when it first starts up. I can't tie it to temperature either since it may hard shift when it's cold or later when it's been run and is fully warmed up. There is no difference in the behavior going into drive or reverse. They're either both good or both rough.

When it's not shifting properly, it acts like a vacuum modulated tranny with a vacuum leak - shifts fine under power but rough at idle.

One of the first things I did to it when I got it was to replace all of the u-joints, the lube in both differentials and transfer case, and seals.

For what it's worth, I get terrible mileage (17 mpg with 50/50 local and highway driving), even with new O2 sensor and 190 degree thermostat. Torque converter not locking up?
 

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99 Tracker, 5 door, 2L, 4x4
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I have the OBD Wiz software. Don't know about its ability to read extended codes.
Not sure, check if you have access to the PIDS..

The hard shifts are always at idle when I'm first starting out or reversing direction. RPM does not seem to be a factor since, when it's not misbehaving, it will shift smoothly from park or neutral to drive or reverse even at fast idle when it first starts up. I can't tie it to temperature either since it may hard shift when it's cold or later when it's been run and is fully warmed up. There is no difference in the behavior going into drive or reverse. They're either both good or both rough.

When it's not shifting properly, it acts like a vacuum modulated tranny with a vacuum leak - shifts fine under power but rough at idle.

One of the first things I did to it when I got it was to replace all of the u-joints, the lube in both differentials and transfer case, and seals.
Sticky solenoid!
For what it's worth, I get terrible mileage (17 mpg with 50/50 local and highway driving), even with new O2 sensor and 190 degree thermostat. Torque converter not locking up?
Check your LTFT, check exhaust manifold for cracks, illegal air..

.... Philip
 

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Discussion Starter · #7 ·
The scanner shows a list of PIDs but none that are related to the tranny as I can see.

I did discover something as I came home tonight. I had checked it at a stop not far from home by shifting it in and out of drive and neutral and all shifts were smooth. Before I shut it off at home, I did the same thing and it was pretty rough. After 3 or 4 shifts, I left it in neutral for a few seconds and ran the rpm up. I immediately shifted it into drive and it was smooth. Maybe a sticky solenoid was responding to a boost in voltage. Are the solenoids accessible externally?

By the way, what is the LTFT? (Little Temperamental Fragile Thing?) On this end, you're dealing with an individual whose auto service career was in the age when smog control meant adding a few feet of hose to the breather pipe to keep the blow-by out of the cab.
 

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By the way, what is the LTFT? (Little Temperamental Fragile Thing?)
Long Term Fuel Trim, should remain close to "0" at idle and 2000rpm

On this end, you're dealing with an individual whose auto service career was in the age when smog control meant adding a few feet of hose to the breather pipe to keep the blow-by out of the cab.
No Need to stress, we are all in the same boat..;)

... Philip
 

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You can disconnect the tranny computer at its connector, and manually shift through the gears (you will not have overdrive, however) and see if the hard shift remains, which will point you to either a mechanical or electronic cause of your problem. If mechanical, you may want to check out an additive called AT-205, which some posters here have had good luck with for this issue.
 
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