After my little break with cars.. (bought a bike), I'm getting my car back on the road. I have no 4th gear. Tranny shop says computer is giving command to shift to 1 instead of 4. I'm ready to go to a local place known for their expertise with electrical work, but just wondering if there is a cheaper way to see if my pcm is faulty.

I'm posting this from an Android app, so I'm not sure of my sig will appear, bit I have a stage 2 Performabuilt with 2500 stall and Trifecta tune


Posted from Camaroz28.com App for Android

 

If a solenoid isn't working, then it is either the solenoid or the signal going to it

 

If you had a laptop, $$70-90 ALDL cable, an TTS Datamaster $EE (free for 20 logs). Or a scanner that supplies transmission status bits you could see what the PCM is commanding. Here is a schematic of a '95 setup, http://shbox.com/1/1995_pcm7.jpg your '94 does not have the PWM solenoid nor the brown wire coming from PCM pin D6 (PWM was added in '95). 1-4 shifting is accomplished by the 1-2 and 2-3 solenoids, called shift encode A & B in the PCM. A ground on the pin from the PCM activates the solenoid so an on = 0 volts and an off = +12 volts if you check the wires. The 1-2/2-3 decode is as follows.. ON/ON = 1st , off/on = 2nd, off/off = 3rd and on/off = 4th . Since the two circuits are common to all gears there is no way one wire or solenoid bad would cause a 4th only shift failure. However if the PCM is not commanding a shift when MPH and TPS criteria is being meet then it could be a tune (has Vincent's tune been messed with ?) or very, very rarely the PCM.. Have you given Performabuilt a call ?? Datamaster will show the status of the control A & B lines and will isolate the problem very quickly..

 

I have talked to Vince, he has reassured me that the 3-4 shift is to be at 19mph, and that the tune is not at fault. I have also contacted Frank at Performabuilt. The transmission was returned and checked out. No problems. A local transmission shop here in MD manually shifted it to 4th. OD is there, so that rules the transmission itself out. My next step is unknown at this point, I thought of just taking it to a place here that is very well known for electrical work, thinking, no HOPING, that it could be something simple.


Posted from Camaroz28.com App for Android

 

Have you scanned the PCM for tranny codes? They don't turn on the SES light. There may be engine codes that affect the trans shifting as well when they set.

 

Only code it's throwing is for an o2 sensor. Light is on


Posted from Camaroz28.com App for Android