I had a trans cooler hanging around from my previous blazer and I decided to throw her on today. I just went for a ride and everything seemed fine until I got out of the woods and onto blacktop. as soon as I hit 37mph-ish the tranny becomes unresponsive like it's in neutral. any idea why? fluid is fine, cooler wasn't plugged, no leaks... first, second and third work perfectly. and overdrive worked just fine this morning.


also I did notice a bang shifting into second gear now that I think of it. which reminds me of this.... (4. 1-2 shift is delayed and harsh, may not shift into OD: TPS needs to be checked for smooth and linear electrical response over the entire range of motion. If not, this must be replaced.) which is from www.twincharoltte.com

2000 ZR2

 

replaced TPS no difference...

 

Did you add trans fluid after adding the cooler?

 

yes I filled it up properly. just disconnected cooler went for a ride still have problem.

 

Perhaps the trans pump was just about to go out and the added resistance of the cooler took it out.
I assume the trans will not shift into each gear manually, right?

Sure sounds like a trans issues instead of an engine. Time to find a good trans shop, if there is such a thing??!!

 

The most common failures to 4L60/4L60E transmissions are 3-4 clutch failure, 2-4 Band and reaction sun shell. What you describe is not any of these symptoms. A transmission shop sounds in order and the trouble is highly likely to be coincidental to the installation of the cooler. What year is this and how many miles are on it? Could this be shifting 1-3 and tcc and missing both 2nd & 4th? If it is you have a broken band.
And yes there are great transmission shops and rebuilders out there. Look for an ATRA (Automatic Transmission Rebuilders Association) Shop
Tranzman

 

I had no bang, grinding, it didn't go gradually... I went off-roading and all of the sudden it stopped working. I wonder if a wire or something electrical came loose? no CEL. shifts perfect 1-2-3 and Reverse... Monday I'm going to see about borrowing a scanner with live streaming data, if I cant figure this out I'm going to buy a master rebuild kit and do it myself.








2000 ZR2 blazer 130k

 

So this morning I picked up some new Dorman cooler lines from advance auto. When I hooked up my auxiliary transmission cooler I had to bend the return line, also I had to bend it back when I took it off. So considering it was all bent out of shape and starting to rust I figured it was worth replacing. I wiggled the main electrical plug while I was down there, had no leaks, went for a test drive, and POOF all of the sudden 4th gear came back! I picked up my old lines and blew air threw them easily. no leaks. so that leaves the plug as my main suspect for not having 4th gear. when the exhaust cools and it stops raining i'll pull off the plug and have a better look at it.

 

but my problems are not over because now when my tranny shifts from 1st into 2nd it's a hard shift. it takes an extra second to engage 2nd gear and with doing so I can feel the vehicle pull forward excessively.

 

Did you go mudding or through a bunch of water? it is very likely the connection got moisture in it from off-roading. try disconnecting the battery to force the computer to re-boot. it is also possible for the moisture/connection to cause high line pressure... put some dielectric grease in the case connecter/plug. fixed more than a dozen 4x4's trans problem either at the case connecter or the computer. sounds like you got it fixed, YEA!!!
Tranzman