I need a new pump for my 4l60e and i basically need to know what PWM stands for and do I have one in my 4l60e out of a 95 z28. Will a pump for a 95 4l60e fit into a 94 4l60e???

 

Pulse Width Modulated.

'94s are not PWM, whereas '95s are.

 

The PWM solenoid actuates the torque converter clutch (TCC). It causes the clutch to engage slowly and smoothly rather than the on/off type of engagement. Not sure about the pump differences, but the 95+ have both the PWM solenoid and the on/off solenoid. Many of the shift kits out there for the 95+ trannies just disable the PWM solenoid and make the on/off one the primary actuator... giving them the distinctive "drop" into lockup like the 94 has from the factory.

 

'94 and '95 4L60E pumps are NOT interchangeable. PWM is as mentioned earlier...Pulse Width Modulated. The '95 4L60E has an extra solenoid on the valve body (PWM Solenoid) to control this. The PWMs function has been explained pretty well above, also.
What part of the pump is bad? Body or cover? If your cover is still good, you can use a late 700R4 body/rotor/vane assembly in a '94 4L60E. You'd be surprised how many people don't know this.

Frank
Cahall Performance Transmissions

 

I am not sure which part is bad. I have a whining coming from under the shift column and a guy i know who rebuilds tranny's said it was a very good chance the pump was on its last leg. I just bought a new GM pump off ebay for $100 bucks and its for a 95.

 

If you don't see anything obvious in the pump, you might want to look toward the torque converter. I've seen many of them make a very pronounced whining noise. Does it do it all the time? Just when it's in gear? Just when the car is moving?

Frank
Cahall Performance Transmissions

 

It does it pretty much all the time. The higher the engine rev the higher the whining. It does it when I am driving as well as if I am in park and not moving.

 

Before you jump right into a pump swap, pull the pan down. Make sure the filter doesn't fall out of the pump without you having to pull on it. A worn out filter seal will suck air, and it'll sound like a whine, also.

Remember, if you don't see anything obvious in the pump, make sure you change the converter, also. 4L60E's have rotor/vane style pumps. It's not common for one to whine. Most pump whines are related to gear style pumps, such as a TH350 or TH400, for example.

Frank
Cahall Performance Transmissions

 

Will a filter seal make my tranny not shift out of first gear without letting off the gas?? Before when it all started it would shift but shift real lazy, I have a shift kit so it was very unusual. Well then 2-3 shift started shifting lazy. Well now first wont shift unless u let off the gas, and if u dont it will slowly reach about 4000rpm and then it jumps into second gear, not lazily but now it feels like it used to but way late. If i give it moderate throttle off the line it pulls hard still until its time to shift, and then it wont. Oh, and i dont have overdrive anymore either.

 

OK...This all adds more to the equation. Is it a Trans-Go shift kit? If so, your 2-4 band and 3-4 clutches are probably cooked. This is the COMMON occurance with a TG kit.

Frank
Cahall Performance Transmissions

 

No sir, its a B&M transpak.