[Firebird1974]

Hello, i have an Chevy Starcraft G20 with an 4l60e transmission. When starting the engine it will shift up to the 4th gear and then it stays in 3th or 4th gear. Running a laptop to it gives codes 66 (3-2 shift solenoid circuit). Have checked and replaced all the solenoids without any result.I can shift any gears with the laptop and the trans is shifting. But is does not shift automaticly. Could this be an pcm fault?. Have checked all the wires and ground straps and ing. key.

Greetings from the Netherlands

 

[Firebird1974]

Thank you for your awnser. Have checked all the wires from transmission to pcm, all in good condition. Now i have the rear wheels from the ground and with running engine in OD and the laptop connected to obd connection. Sometime it shift good 1,2,3,4 and back when i press the brake pedal. But when it shifts good i read 0,7 A on force motor and 0 % on the tcc solenoid(when brakes are applied) . When it is not good then the transmission will shift up but not down and read 0,1 % on the tcc solenoid and 0,14 A from force motor. A fresh restart of the engine will let the trans shifting good for about 1 or 2 minutes.

 

[Firebird1974]

Have cleanded the connector on the transmission, no oil in the connector and all the connection pins are in good condition. Have removed the pan again and checked the wires and connections again with no result. Pink wire from ing. key reads 12,5 volts with engine off. All the groundings are also good. Why would it downshift sometimes and most of the time not?. Could it be the chip in the pcm?.

 

[Firebird1974]

When i connect the laptop to it i see an lockup for 1% and then the force motor read's 0,16 A instead of 1,00 A. And when the trans is working good i read 5,6% at the tcc and 1,07 A at the force motor with trans in 2nd gear free rolling (wheels from the ground).

 

[Firebird1974]

Have the transmission changed with a rebuilt trans and still got dtc 66 3-2 solenoid circuit. This morning when i drove the van it was shifting fine. When the engine is operating temp. the transmission stay in 3th gear and will not shift back. Very weird that i would up an down shift with cold engine and not when engine is at operating temp. Checked VSS, pulled connector off and have only 2nd gear. When i do a restart of the engine it shifts from 1 to 2 to 3 and is stays there. Only cold engine the trans works great.

 

[Firebird1974]

Have disconnected the trans connector, 2 pink wires reading 12 volt and nothing on the red wire. Can i jump 12 volts on the red wire?

 

[Firebird1974]

Have replaced the ECM, iit is shifting very fine now. Upshift 1,2,3,4 OD and downshift is also good. But still have the cod dtc 66 3-2 solenoid circuit. Checked all wires, condition like new. On the new ECM i read if code exsist check the prom. Can a prom give valse dtc readings ?.

 

[Firebird1974]

Hello, tanks for your anwser. The van is shifting fine now 1,2,3,4 L/U and codes are gone. Could not clear the codes with gmtd scan tech. After disconnecting the battery cables for 24 houres and connected again the codes where gone. No SES light anymore.