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sprinkles08, ASE Certified Technician
Category: Transmissions
Satisfied Customers: 23100
Experience:  Chrysler/Dodge/Jeep master tech ASE Master and Advanced Certified, Chrysler/Dodge/Jeep Master Certified, Trans Specialist
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My 1994 j30 has an intermittent trans problem. I suspect

Customer Question

My 1994 j30 has an intermittent trans problem. I suspect some sort of electronic control unit. It normally runs fine and down shifts up shifts perfectly. But every once in a while it stays in a lower gear and won't up shift. Shut the car off, turn the key to restart an trans light blinks on dash after problem. If I pull over and restart and drive again, it is usually gone. Help, what could it be, normally runs fine for week's, and then out of now where this happens.
Submitted: 2 months ago.
Category: Transmissions
Expert:  sprinkles08 replied 2 months ago.

Hello and welcome to JustAnswer!

It sounds as if you're transmission is going into limp in. When the trans controller sees a failure that will prevent proper operation it will set fault codes and lock you in a single gear to prevent damage.

There are many possible causes for limp in including speed sensors, the range sensor, solenoids, wiring, the trans controller itself and internal transmission issues.

The first step in diagnosing the problem will be to use a scan tool to see what fault codes are set and then testing can be one from there based on the findings.

I hope that helps! My goal is your satisfaction today. If you feel I've been professional and helpful, your 5-star rating at this time is most appreciated. However, if you still need my help you can reply back here and I'll respond as soon as possible! Thank you!

Customer: replied 2 months ago.
I was hoping Jay the infiniti expert would have gotten back to me with some more specific info, I already know what you told me. The trans runs literally flawless and this happens very rarely. Does this transmissions tcm have a likelihood to fail from past experience or market history.?And where is the tcm located?. Rather than pulling trouble codes on an obd 1 car, I would remove the transmission module and test it it, if you can tell me there is a way to test it for being bad. Even if other parts internally are bad, I would like to rule the TcM out first. This is something I could replace my self, if it is extwrnal to the trans. I am able to get the module for 265.00 from a1 cardone. I am looking for more than what a transmission shop is going to tell me, in order to get my car in the shop. What you told is what I shop would tell me.
Expert:  sprinkles08 replied 2 months ago.

There isn't a way to test the module. If all possible causes for a given fault code can be ruled out then the TCM can be condemned and replaced. TCM failure is possible but not that common.