Quote:
Originally Posted by Rich84
New Ls swap..When I drive the truck at initial startup it shifts fine. Park the truck for a few minutes and drive it again and it will not shift into 4th gear.
The fluid was not too clean when I dropped the pan to change the filter.
It also seems like it might be starting in 2nd gear sometimes.
P0753 shift solenoid is the only code.
Is it as simple as replacing the solenoid?
|
P0753 is a electrical fault code for the 1-2 shift solenoid circuit. Check PCM Red Connector Pin 48 for the terminal being backed out, Same for the Trans Plug Pin A.
#1 Disconnect the PCM. Key on, Using a DVOM com lead hooked to ground, Probe Pin 48 of the Red connector with the key on. The DVOM should read close to battery voltage.
If power is present....Ground pin 48 with a 5 amp fused jumper. If it blows the jumper fuse, You have a short to B+.
On a good circuit, Grounding pin 48 will activate the solenoid & you will hear a audible click.
#2 If no voltage is present in step #1......Key off, Hook the com lead to a battery hot source, Probe Pin 48.....If it now has battery voltage (it will read negative voltage because the polarity is reversed, Not a concern), You have a short to ground somewhere in the 1-2 solenoid circuit.
Unplug the Trans.....
If you no longer have battery voltage.....The short is in the internal trans harness or the solenoid itself.
If you still have battery voltage.....The short is in the engine harness.
#3 If you can't get any feedback from the 1-2 circuit at the PCM connector in the above tests.....
Unplug the trans, Key off, Ground Pin A of the trans plug, With DVOM com lead still hooked to B+, Probe pin 48.
If the DVOM now reads battery voltage.....The wire between the PCM & Trans is good.
Check the trans connector for bent/laid over pins, If that checks good....Replace the internal harness & 1-2 shift solenoid (All solenoids would be recommended)