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Joe  Barfield
Joe Barfield, Master High-Tech
Category: Car
Satisfied Customers: 1349
Experience:  Transmission Tech - Management Master Winner 3rd place Entire US Southeast region #1 after masters
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Im an ASE Master tech myself, but Ive run into a problem

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I'm an ASE Master tech myself, but I've run into a problem that my alldata doesn't go into too much detail about.

On my customers Isuzu, the trans would only engage in reverse. After pulling DTC's we found a TCC fault code, we replaced the TCC and found no difference. There are 2 electrical connectors on the drivers side of the trans. When we disconnect the round one behind the selector switch, "Nuetral safety switch" the trans engages in 2nd and 3rd and reverse! We cleared codes, unpluged and pluged back in the PCM and checked for any faulty wiring. It seems that the trans is going into a default mode, but second and third and reverse engage without any slippage, illiminating clutch problems. Does this sound more like a PCM problem? Remember, the round 5 or 6 wire plug along the drivers side of the trans allows the trans to work "with limits" when UNPLUGED and only reverse "WHEN PLUGED IN".
Hello, So No Foward.....Even in Manual Low ?......Thanks Joey
Customer: replied 6 years ago.

Hi Joey,

Thanks for responding, When the round electrical plug is in on the side of the trans, it won't engage in any gear except reverse.

When you unplug it, you can engage 2nd, 3rd and reverse with no slippage.

Ok,Your problem is your PWM Solenoid is faulty and could have burnt the low band.....which results in No-Foward movement.....Thanks Joey
Customer: replied 6 years ago.

What does PWM stand for?

Is it the shift lock solinoid?


So, when you disconnect the round electrical plug on the side, does that put the trans into a default mode to only have 2nd and 3rd and reverse,


But when it's pluged in, the trans only has reverse?????

Hi,many imes this is caused by servicing the trans....& damage to the wire harness can occur just by placing the filter between the harness & filter......Please hit the accept button if i was of help to you or just ask another Question....Thanks Joey.....the pwm is the pressure solenoid for the low band....& id have to say the Band is burnt up as when you plug it in you have no foward
Do you Understand.....Its asking for the band to apply for foward....if its burnt you get nothing
Customer: replied 6 years ago.

Yes, I'm willing to replace the pressure solinoid for the low band first, I should see somekind of results other then what I"m getting now right, even if the low band is burnt? It should atleast try to engage?


Do you have an OEM part number for me to try and locate one from a dealer?

Hi, By the way thats a 4L30-E CHEV. Transmission......and you can try that however once it goes bad it will burn that band in a heartbeat.....ive built hundreds of these trans....90% of the time thats exactly what happens.....its to late you will not feel anything.....thats a very thick steel band, however it is lined very,very thin as a result when it looses pressure its gone!!
Customer: replied 6 years ago.

Thank you Joey, this one had us stumped and even when I took it to our local trans shop for some brain storming, they were afraid to just bench overhaul it because they weren't sure if it would cure what we were after.


Do you have an OEM number for the solinoid and the low band??????

I have many soures, the best band & solenoid are sold from "Trans Star Industries".....www.trans only thing they should see is a bad hard part damage at all most of the time....just sand the Drum it should be fine
They have locations all over the U.S.
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