Dreaded P0758 code 2-3 shift

[laxman21]

P0758 code 2-3 shift solenoid B circuit fault.


So, how hard is this to replace? What's involved?



This is what I expected since I only have 2nd and 3rd gears.


99 blazer.

[Chris Stewart]

Sorry, it don't look good.
See if it'll shift manually...if not then the 3rd gear clutches are likely wiped and the trans will have to come apart$$$.
Roostra brand solenoids are reported better than stock GM pieces.

[Brian_D]

laxman21,

if I understand correctly, (the '99 Blazer LT w/ 4L60E transmission), no 1st or Overdrive; 2nd, 3rd, and Reverse are fine.

With the 4L60E transmission, this is called Failsafe mode (3rd gear starts unless the selector is placed in D2 or D1,then it has second gear starts). In failsafe mode, you will only have [R] [2] [3]. As seen from the shift pattern below, the most frequent cause is a bad 1-2 Shift Solenoid (approx $20 dealer part) under the transmission pan.

Solenoid
Gear 1-2 2-3
---- ---- ----
1st On On
2nd Off On
3rd Off Off
OD On Off

[laxman21]

Originally Posted by Brian_D

laxman21,

if I understand correctly, (the '99 Blazer LT w/ 4L60E transmission), no 1st or Overdrive; 2nd, 3rd, and Reverse are fine.

With the 4L60E transmission, this is called Failsafe mode (3rd gear starts unless the selector is placed in D2 or D1,then it has second gear starts). In failsafe mode, you will only have [R] [2] [3]. As seen from the shift pattern below, the most frequent cause is a bad 1-2 Shift Solenoid (approx $20 dealer part) under the transmission pan.

Solenoid
Gear 1-2 2-3
---- ---- ----
1st On On
2nd Off On
3rd Off Off
OD On Off

That's the symptoms. But the snap on code reader said P0758 code 2-3 shift solenoid B circuit fault.



Pathetic off the line unless shifted to d-1 or d-2



Where are the servos located?

[laxman21]

Found this link. It's for a toyota, but it gives you the idea of what to do.


http://www.tankota.net/repair/Repair...a/cip0753p.pdf

[Brian_D]

laxman21,

here is a picture of the 4L60E valve body



the 1-2 shift solenoid is located in the front left-hand side of the valve body. the 2-3 shift solenoid is located immediately to the right. both solenoids will have a two-pin wire harness connection (+12VDV and Enable/Gnd).

Testing the shift solenoids:
1. with the transmission pan removed, turn the ignition key to ON (do not turn to RUN or START)

2. using a multimeter, probe the two-pin wire connector (to the solenoid) for +12VDC (one wire carries constant +12VDC, the other wire is the Enable/GND lead from the PCM)

3. using a small jumper wire, short the Enable/GND lead to ground and listen for an audible click from the solenoid. NOTE: use extreme caution when testing - key to ON not RUN; engine NOT running; short ONLY the Enable/Gnd lead and NOT the +12VDC.

[laxman21]

Just got the call from the tranny shop. They are gonna replace both solenoids and fluid change and filter.

[tyler6501]

I'm having this same problem. The code that is coming up is P0758. I tested the resistance on the soleniods and all are within specs. I also tested the soleniods by applying power to the soleniods and all make an audible clicking noise. I also tested the resistance of the force motor and it was 4.5 ohms which is a little low. I'm kinda stuck on what to do next. If the soleniods are all good could there be a wiring problem??? if not a wiring problem then what could it be???