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skyhigh4by

Typical lock/unlock issues PLUS

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Just picked up a 98 24v that is having the typical TC lock/unlock issues BUT also sometimes the TC is not unlocking at all and when coming to a stop it stalls the engine out. Put it in park or neutral it fires back up and then you have to play the throttle to get it rolling or it will just stall out again also just driving around I can tell the TC is randomly locked because the engine will really struggle to pick up speed (sometimes I can tell TC is unlocked and everything feels fine). I haven't done any testing yet but from what I can see there are several wires wrapped with tinfoil :doh:, I know it has a new alternator, new lift pump, new interstate batteries(connections look very clean) and it has been to a trans shop a couple times but not sure what has been to the trans itself if anything.

 

Mostly I am wondering if the TC staying locked when coming to a stop + being locked when it shouldn't be is related to the typical locking/unlocking/hunting issues or if Im trying to chase down 2 totally separate problems. I will start with the alternator testing and tracking down as many ground points as I can. 

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You need to contact @Dynamic he's our site transmission guru. 

 

It could be a torque converter issues something damage inside of it. There could be a short to ground on the lockup signal wire causing the random lockup issues. 

44 minutes ago, skyhigh4by said:

I haven't done any testing yet but from what I can see there are several wires wrapped with tinfoil

 

Get rid of all the tin foil. Also, check for added ground wires or modified wiring and return all wiring back to stock.

 

Before Testing - IMPORTANT PLEASE DO NOT SKIP!

 

Before doing any testing of the alternator for AC noise, make sure to remove any and all wiring modifications. Return the electrical system back to stock. Make sure there is no extra grounds, relocation of ground wires or noise filters installed before testing the alternator. It has been brought to my attention that wiring mods can and will provide false passing grades for the alternator. The entire electrical system should be left stock and unmodified so you (the owner) are alerted sooner to impending alternator failure. Stock system will show AC noise issues much sooner than modified system which will mask the issue and then typically cause damage to ECMPCM or VP44 sooner.

 

Funny part, is I just last another alternator last night. Very easy to detect with stock wiring and give plenty of early warning of it going south only if the wiring is completely stock. Mine has a very surgy / jerky cruise control because the tach signal is muddy up with AC noise. 

 

I did stop by a local shop in Ontario, OR and talked with the gent there that has 31 years of experience. Basically in a nutshell excessive high current loads will cause the diodes to over heat and then fail. In other would starting the truck and leaving to sit and warm up and idle against the grid heaters is really hard on the alternator. 

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UPDATE...

i removed the alternator from the equation and the hunting/funny shifting has completely disappeared. The TC lockup issue is still there though. Intermittently I have to be on the throttle to get moving or it will stall or I have to quickly get it in to neutral when coming to a stop or it will stall. Also very poor acceleration due to being locked up

 

My local parts store can not source a new alt only reman. I know what I have is not the original alternator so what can I do to try to remedy that problem? 

Edited by skyhigh4by

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Thank you. Are there any mods, tricks, or any particular maintenance and things I should check to secure the longevity of a new upgraded alternator? Does anyone know what’s causing the diodes in them to fail? 

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When the throttle drops to idle validation voltage of about .5 v it should unlock.  If that voltage is too high it might be keeping it locked up.  Wiring or APPS issues could be the problem, but not necessarily

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