Engine/Transmission (1994 - 1998) 47re starts out in 3rd

[LNaugle]

I have one I could possibly use some help on... 96 truck with 47re starts out in 3rd when put in drive. manually put it in 1st and it starts out in 2nd... 2nd to 3rd shift positive feeling, tries to shift to od but hunts back and forth. after warming up got od to work but let off pedal and starts downshifting... the whole time this is going on the tach jumps around. just test drove going to start diagnosis next. wondered if anyone has some pointers... ????

 

[BigPapa]

the whole time this is going on the tach jumps around.

This is most likely your issue. The trans is in "limp mode". I'd bet your alternator isn't charging and your A/C won't work. Check the ESS and wiring. It is right on top of the harmonic balancer. Gap should be . 050. Don't use a steel feeler gauge. I think a credit card is close to . 050, or is it 2 credit cards? I can't remember. If the PCM doesn't know wht the engine rpm's are it puts the transmission in limp mode and will not turn the alternator on or the A/C compressor.

 

[LNaugle]

ended up to busy to get back to this truck but i am pretty sure the alt is charging... . my eye would have caught that gauge not reading right but will check. tach never went to "0" , just bouncin... perfect at idle... tps cause these problems? thanks Big Pappa will check anyway... maybe wiring... truck does have 268,000 or so on it.

 

[cerberusiam]

3rd gear starts are usually the gov solenoid. It that has not been changed it is worth changing. The OD hunt is likely the TPS having a bad spot in it or just nit reading correctly, or, even the gov pressure solenoid.

 

[LNaugle]

Thats what i was thinkin cerb... . thanks for the 2 sense worth... think i am going to bring it in on the lift and put trans psi gauges on it and hook up scanner and run it... might be a few days... we are pretty busy and i think it has a couple bad delivery valves due to lil hard start and missing for a second... no white smoke... will let everybody know what i find...

 

[LNaugle]

so we hooked up gauges and scanner and found trans putting out proper psi and gov solenoid not... . replacing solenoids and transducers and adjusting the bands. will see what happens..... also found the cranksensor wires had been cut and spliced... replaced with good used one and problem gone. still has hard cold start... plunger coming up but can hear what sounds like swooshing noise in pump when starts. we replaced the lines and fuel heater gaskets and hoses and lift pump last year so... . ? almost seems like overflow valve making the noise.

 

[BigPapa]

..... also found the cranksensor wires had been cut and spliced... replaced with good used one and problem gone.

I'd bet this alone would've solved your issue.

 

[LNaugle]

changed the crank sensor and drove on lift and only fixed the tach... . was hoping that was all it would have been... wasn't... . changed out the solenoids and transducers and all is well... even found where one of the hoses we swapped out had come tiny bit loose , double clamped and starts cold perfect. thanks for all the help & hope this helps others.

 

[cerberusiam]

I'd bet this alone would've solved your issue.

Crank sensor just controls charging, AC, and tach on these 12V's. The Trans is controlled out of the PCM with limited sharing of data from PCM to EC. The EC can be toast and the truck will still drive and shift fine.

 

[BigPapa]

Crank sensor just controls charging, AC, and tach on these 12V's. The Trans is controlled out of the PCM with limited sharing of data from PCM to EC. The EC can be toast and the truck will still drive and shift fine.

Wish that was the case with mine... ...