Code 28

[93 K1500]

Alright just finished replacing my tranny- 4L60 E.
Started up drove fine for like five minutes then all the sudden boggs way down off the line slams into second I limp home and pulled a code 28, Can someone please help here I am at a loss. Could it also be the PCM going out ????

 

[badazzbulldog]

Transmission range pressure switch

 

[1LEG]

Not a tranmission expert. but are you sure the new trans is a 93-94 4l60e. in 95 they changed a few things in the 4l60E.
Next ask the tranmission guy if they used all new electronics and wiring inside the trans, i was told that it's important to use all new parts.

 

[93 K1500]

Yes All new electronics -

 

[93 K1500]

Last night I was reading that the code 28 Trans range Pressure control switch was only on 94' plus can anyone confirm this, Because I also found code 28 listed as PCM circ. # 2. ?????????

 

[rhino]

It was in 93 also... The fluid pressure switch assembly consists of five pressure switches (2 normally closed and 3 normally open), and a fluid temperature sensor combined into one unit and mounted on the valve body. The PCM supplies battery voltage to each range signal on three separate wires. By grounding one or more of these circuits through various combinations of the pressure switches, the PCM detects what manual valve position has been selected by the vehicle operator while idling with the engine "OFF" P/N will be indicated. If range signals "A" and "C" are 0 volt, or all three signals are 0 volt for 1.5 seconds on the diesel engine, or 2 seconds on the gasoline engines, DTC 28 will set. When DTC 28 is set, harsh shifts, no TCC will occur, and no fourth gear if in hot mode. I will see if I can post a pic.

 

[rhino]

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[93 K1500]

Thanks I guess its time to start checkin man I hate elect. issues maybe ill get lucky and its just a bent pin. But if that is the case why does it run good for a couple min. then all hell brake loose????

 

[1500z71]

It was in 93 also... The fluid pressure switch assembly consists of five pressure switches (2 normally closed and 3 normally open), and a fluid temperature sensor combined into one unit and mounted on the valve body. The PCM supplies battery voltage to each range signal on three separate wires. By grounding one or more of these circuits through various combinations of the pressure switches, the PCM detects what manual valve position has been selected by the vehicle operator while idling with the engine "OFF" P/N will be indicated. If range signals "A" and "C" are 0 volt, or all three signals are 0 volt for 1.5 seconds on the diesel engine, or 2 seconds on the gasoline engines, DTC 28 will set. When DTC 28 is set, harsh shifts, no TCC will occur, and no fourth gear if in hot mode. I will see if I can post a pic.

Sorry to comment on such on old post but I threw a code 28 and lost fourth gear. Transmission overheated last summer. What is hot mode? I had a code thrown for the temperature sensor too (58).

 

[94GMCK1500]

I just had my 94 GMC 4L60E rebuilt. Guy says full rebuild with all new GM parts and solenoids.. Drove it home, it seemed little sluggish but I knew it needed a tune up and just had the intake done so figured timing may be little out.

Did full tune up with AC Delco, plugs, wires, rotor and cap. Fuel filter was done less then 3k miles. I got codes popping up when I went to set timing... 14,28.33.42.54.66. I unplugged what I was told is the ignition wire ( actual name slips my mind )... The timing was out, I set it to 0 degree as it's called for... I cleared ecm by unplugging battery... I now have the codes 42, 66... My transmission feels like its in limp mode... I haven't checked the + (pink) wire for power yet, doing that tomorrow...

Would it safe to say that it's the ecm if the pink wire tested fine...? Or am I missing something else ? I gave much as I feel is enough info... Have any questions, I'm open to answering what I can...