Chevrolet Repair Questions? Ask a Mechanic for Answers ASAP
the most likley cause is the transmission fluid pressure valve switch. It is located
under the transmision pan on the valve body. If you have an ohm meter you can remove
the switch assembly and check each individual switch on the assembly. On the under side of the switch you will see multiple "plunger" switches. PLace the leads of the meter
on each side of the "plunder" switch contacts (little rivots) and press the plunger down with the eraser end of a pencil. Most of the switched will be open till pressed with one or
two being colsed until pressed Hope this helps...
There would be other codes stored. What engine do you have and in what vehicle?
When it acts up, does it move? it hould defalt to 3rd gear. you may have an issue with
a valve hanging up in the valve body. no other codes stored in the computer?
The trans. pressure switch is a multiswitch assembly which tell the computer which
gear it is in. Without pressure, no switch activation. This is why I think you may have an internal presure loss issue. The first step is to make sure the fluid level is correct. If you have a scan tool, you need to verify whether or not the switch data is correct while the condition is present. Is there any abnormal noises from the transmission while the condition is present? I am doing the best I can without actually putting my hands on the vehicle.
Here is a wiring schmatic for the pressure switch involved. Check the ignition power
circuits while the condition is present. This will rule out the power loss. When you say pressure is great, you checked it with a gauge correct? Do you recall the pressures?
Here is the connector end view at the trans...
Connector Part Information
1-2 Shift Solenoid Valve Control
2-3 Shift Solenoid Valve Control
Pressure Control (PC) Solenoid Valve Controlled Power
PC Solenoid Valve Controlled Ground
Transmission Solenoid Power
Transmission Fluid Temperature (TFT) Sensor Signal
TFT Sensor Ground (4.3L)
TFT Sensor Ground (4.8L and 5.3L)
TFP Switch Signal A
TFP Switch Signal C
TFP Switch Signal B
3-2 Shift Solenoid Valve Assembly Control
Torque Converter Clutch Solenoid Valve Control
Torque Converter Clutch Pulse Width Modulation Solenoid Valve Control
Ok, you replaced the fluid pressure solenoid, but not the pressure manifold switch assembly? I may have misled you with my first terminology. The code is for the manifold switch, or transmission fluid pressure manual valve position switch. This is a pic and description:
Important: Seven valid combinations and two invalid combinations are available from the TFP manual valve position switch. Refer to the Transmission Fluid Pressure Manual Valve Position Switch Logic table for valid/invalid combinations for range signal circuits A, B and C.
The transmission fluid pressure (TFP) manual valve position switch consists of five pressure switches (two normally-closed and three normally-open) on the control valve body that sense whether fluid pressure is present in five different valve body passages. The combination of switches that are open and closed is used by the PCM in order to determine the actual manual valve position. The TFP manual valve position switch, however, cannot distinguish between PARK and NEUTRAL because the monitored valve body pressures are identical in both cases.
The switches are wired to provide three signal lines that are monitored by the PCM. These signals are used to help control line pressure, torque converter clutch apply and shift solenoid valve operation. Voltage at each of the signal lines is either zero or twelve volts.
In order to monitor the TFP manual valve position switch operation, the PCM compares the actual voltage combination of the switches to a TFP combination table stored in its memory.
The TFP manual valve position switch signal voltage can be measured from each pin-to-ground and compared to the combination table. On the automatic transmission (AT) wiring harness assembly, pin N is signal A, pin R is signal B, and pin P is signal C. With the AT wiring harness assembly connected and the engine running, a voltage measurement of these three lines will indicate a high reading (near 12 volts) when a circuit is open, and a low reading (zero volts) when the circuit is switched to ground.
The transmission fluid temperature (TFT) sensor is part of the TFP manual valve position switch assembly.
Very easy, remove trans. pan and it is right there. 2 short bolts and 3 long bolts (5 total).
Do not over tigten these bolts. only should be 6 to 10 ft. pounds.