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A General Fluid Flush Interval for Early A604's ?

2290 Views 8 Replies 5 Participants Last post by  valiant67
My '90 Grand Voyager just gave me its periodic transmission refill notice - 3rd gear lockout. Current mileage is around 148K, with 13,000 miles and 34 months since the last flush, with ATF+4.

A flashing light would be so much better than this method of communication, since it always results in an awkward moment on a high-speed roadway. And finding out what the specific condition is requires a visit to a dealership, one of which charged me for over an hour of shop time the last time I was curious enough to investigate.

Having looked through the volumes of communication on these early transmissions, I'm still not sure what the recommended service interval would be for fluid. Haynes says two years or 30K miles. I've seen 15K from more than one source. Driving this van about 5-6 K per year, I know that it doesn't leak, and that currently the fluid looks pretty clear. So, I'm wondering what the recommendation would be, and while we're at it, how do you flash one of these TCM's ?
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1966 Crown Coupe, 2016 200 S AWD, 1962 Lark Daytona V8.
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If the ATF is full and fairly clean still, then I think that you will need more than a fluid change to get it out of limp-in. There is a fault code stored in the TCM that will help us determine the reason.
There were other scan tools (Snap-on, OTC, etc) that can read OBD 1 Chrysler codes. The dealer can't justify going over the base diagnostic charge just to read fault codes. Call around.
You will need a dealer for a TCM flash if one is possible. TCM's weren't flashable until 1994. Yours may not be original. Flashable TCM's are recognizable by the cooling fins on the housing. There may be an authorized software update sticker soft_label.gif on or around under the hood if the flash has been done. The latest software (4761847AA for the 3.3L equipped transaxle) was released late 1995. The new software may a huge improvement in shift quality and was less prone to faults. If you don't have the newer style, you will need one and it may have the latest flash in it.
ATF change intervals will vary by duty and conditions. It really doesn't sound like you need new fluid at this time.
 

· Super Moderator
1966 Crown Coupe, 2016 200 S AWD, 1962 Lark Daytona V8.
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17,287 Posts
Stick-shifts were very rare, even when these were brand new and only available with the 2.5L 4-cyl.
It would still be nice to know what the stored fault code is in order to know how bad the situation is. A fault code is a good starting point. (Some fault codes were 'cured' with the TCM software flash described below.) Then decide what to do.
This is the TSB for the TCM reprogramming update: http://www.robskorner.info/faqs/TSB/18-24-95.pdf
 
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