Engine/Transmission (1994 - 1998) Overdrive & Loss of Speedo etc.

[mcquigley]

Help with OD pop out. 94 4X4 automatic 2nd generation. I can be driving along and then I loose OD, Speedo, Tach etc. All I have to do is turn the key off then on and it works fine. Have checked ing, fuses, wires etc. Sometimes it happens after 2 miles sometimes not until 20 or more. Have had a tester hooked to the ign and still all 3 wires hot. Doesn't matter if hot or cold out or if engine is either. Have checked gounds, wires to PCM, just about everything. Problem in PCM maybe. Anyone having an idea please let me know. -- email address removed -- Thanks

 

[Ghost Rider]

Not sure about the tach and speedo going out, but I just had mine act that way with the O/D. I was at Indy on the weekend, called Dave at Goerand's Trans just in case he might be there. He wasn't but checked in the shop and got my message and called back. Help me trouble shoot and found it was my Speed sensor in the rear of the transmission. Sent me a new one mon. got it wed. Solved problem, best cust. service I ever had. Like I said, my tach and speedo kept working, just lost O/D.

 

[hsmith]

Yep, sounds like you need one of those cheap plastic speed sensors.

 

[rattle trap]

my vote is pcm connection. .



check and see if your ac cuts off at the same time.



you may have to do a wiggle test on the connectors.



vss does control OD and speedo but doesnt really have a direct correlation with the tach.

 

[tp0d]

Try unplugging the crankshaft sensor to see if it does the same thing, just all the time. (i`m not sure if the speedo is affected by that, but tach and od is)

Definetly sounds like a connection problem, a ground possibly, and/or have you checked your batteries? If the voltage is low in one, it can affect the other. Dirty terminals can do that also

It isnt your ignition, cus your engine would die at the same time, due to the shutdown relay being controlled by the ignition.

good luck

-j

Ohya, Welcome to the TDR! Good to have ya

 

[FFredrickson]

similar issue today

I lost speedo,tach,O/D off,and all gauges are out. Radio works, A/C works, lights all work. We also checked all fuses and relays. Possible pcm. I need help before I spend lots of dough.

 

[rattle trap]

have either of you guys tried to pull codes yet?



the ac working would tend to make me believe the ecu is still functioning atleast partially since the pcm handles ac request.



another way of checking ecm function is check vref at the sensors.

 

[LandShark]

There is no ECM on a '94.
It is odd that the AC works, but not other functions. Does the 'wait to start' light function correctly? Pulling codes by doing the 'on-off-on-off-on' with the key may help.
Also, do a search on my posts from last summer when I had to replace my PCM; they may help you.