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98 cherokee shift solenoid b issue

mygreen98

NAXJA Forum User
Location
wisconsin
1998 cherokee xj - 4.0 with aw4 132xxx miles

-problem: when i use my jeep and put it in drive it will start off in third gear. It wont downshift while driving and occasionaly wont lock up on the highway. If i shift into 1-2 it will go into first. if i shift through the gears they all work but it still wont down shift. It was throwing code for the shift solenoids so i ordered new ones(all 3). i took the old out(which still tested good). So far this is what i changed: all 3 shift solenoids, trans filter and fluid(drained, refilled, and drove, then repeated twice), changed the tps, adjusted the cable, and cleaned the nss, and switched the tcu with a junkyard tcu. Still no change. Wont downshift or drop to first from a stop. Im at wits end with this thing. Any help or suggestions would be much appreciated. im still throwing code for shift solenoid b. thank you
 
What you describe are the symptoms of no connection between the TCU (Transmission Control Unit) and the transmission itself. It is probably due to lack of power to the TCU or a bad ground at the transmission.

Make sure the ignition is OFF!!

An easy way to test for power and ground is to pull the connector off the TCU (on your 1998 it is located on the transmission tunnel just above and toward you from the gas pedal). The connector has three fat pins on one side and two on the other, with smaller pins in between. Holding the connector so the three fat pins are on the right, probe the second pin from the right on the bottom row -- it should show battery voltage. Be careful, you don't want to short this pin to anything else!

Now set your meter to ohms and probe each of the three fat pins on the top row. Each should show about 13 ohms resistance -- if they show significantly more and all are the same, you have a bad ground. If only one or two shows excessive resistance, the individual solenoids are bad or have poor connections.

Bad connections can occur within the transmission, the connector at the transmission, the connector right next to the transmission oil dip stick, or in the wiring harness itself.

The approach I would take if it isn't a bad ground (all solenoids show high resistance) or lack of battery voltage is to probe the connector next to the transmission oil dipstick. If it shows the same excessive resistance then I would probe at the connector at the transmission.

Report back what you find and we will help you focus on the trouble spot.
 
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Sorry for not responding. After probing all the wires 1 wire came back 0. It is a blue wire with a white line. Now that the jeep is coming out of storage again I'm getting this fixed. Only problem I'm having now is I can't see where the connector is on the trans. I followed the wires back and they go behind the linkage and I can't seem to find them on the other side.
 
Sorry for not responding. After probing all the wires 1 wire came back 0. It is a blue wire with a white line. Now that the jeep is coming out of storage again I'm getting this fixed. Only problem I'm having now is I can't see where the connector is on the trans. I followed the wires back and they go behind the linkage and I can't seem to find them on the other side.
 
What year do you have? Any diagnostic codes? Have you measured the resistance of the solenoids at the trans computer and described above?
 
No I haven’t tested it yet I just found this tonight I’ve replaced every solenoid new basically all of what the guy above done and still throws the code shift solenoid b bad it will not Down shift and it always pulls out in drive and will not shift into second gear always skips it when it first started I could turn the Jeep of and back on and it would work fine till I turned it off and started again but now it’s always in drive when I pull out I have to manually shift it and it still skips second gear
 
D-tomb, (is where I'm heading iffn I dont get this issue wrestled to the ground), seriously same issue basically, wondering if you ever got to the root of the problem. I did not see this thread and started a fresh one this spring. I may be close to solution but hope you found the magic fix.
thanx!
 
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