Engine/Transmission (1994 - 1998) Won't shift into high gear

[radar doctor]

Got a 1998 12 value, 48r transmission, automatic. . starts off normal,,,shifts normal,,when it's time to shift into high gear, it won't shift,,,,a couple of weeks ago,,, it did this and it cleared up and ran fine,, now it's back at the same thing... It runs 55 mph at 2000 rpm,,,and wont go into hi. . gear... . Any idea's?? Tks doc

 

[fest3er]

A '98 with a 48R? Hmmm. I think you mean a 47RE, unless you changed it.

If you are saying it shifts 1-2-D but doesn't engage overdrive, it might be the temp sensor: the PCM could be thinking that it's extremely cold or extremely hot and won't shift into OD. If you're saying it shifts 1-2-D-OD but doesn't lock the torque converter, that's a different story.

 

[ewcmr2]

Have you checked the really simple stuff? Like the OD off button on the dash...



Otherwise with the 47RE Over Drive is controlled by the computer (DCM?) If a sensor is out of range it will lock out OD.

 

[JohnBoy5]

i have seen this one time before. the only thing i did was pulled ther relay and fuse to the trans. it was really dirty looking cleaned it and its been fine since. i am not 100% for sure thats all that was wrong with it as it was not my truck and we were in the middle of nowhere with no tools. check it out...

you might even also change the relay.

 

[budnate]

a good start, https://www.turbodieselregister.com...7re-automatic-some-common-troubles-fixes.html

 

[radar doctor]

Thanks to all of you that responded... . got her in the shop now... doc

 

[jkh]

Hey fest3er,

You mention a temp sensor for transmission trouble. I was wondering if there was such a thing because my Goerend transmission does some really strange things when it starts to get cold out and the colder it gets it seems like the worse it gets.

It will try to shift to second then go right back to first. It will do this a few times, then it might get all the way to third and suddenly shift back to first. If it finally gets into O. D. and locks theT. C. it will go for a while then unlock and downshift,sometimes to third, sometimes to second. I try to catch it when it locks up and throw the mystery switch in, that holds it and keeps it from unlocking.

It only does this when it starts to drop below 60 outside,but not real bad until it gets to 30 or below, that is when it acts as bad as I described.

Thats why I was wondering about a possible temp sensor.

I e-mailed Dave Goerend but he never got back to me.

Where is it and do you know if it could be my problem?

 

[JohnBoy5]

well if i am not mistaking in your 97 that woudl be a 47 "RH" there is a temp switch in that trans but its only to turn on a light on the dash telling you the trans is too hot. i am pretty sure its not a temp sensor. so i dont think it will control the shifing. if i were you i would give dave a quick call and see what he says. trust me he knows best and prob better then anyone on here. i also bet hes more then willing to help in any way!

 

[WilsonF]

96 and after have the 47 "RE" and there is a sensor that will not allow the trans to go into OD when the fluid is too cold.

Floyd

 

[JohnBoy5]

Ok i stand corrected. Sorry about the incorrect information

 

[jkh]

does it only affect the shift to O. D. because all my shifts are a mess when it is cold.

I know that about Dave. He is great ,he even helped me with a problem on our olds mini van, probably saved me a couple hundred bucks just by telling me to change a couple springs. I hate to call him because he always seems so busy, but if e-mail doesn't work I guess I will have to.

Thanks.

 

[JohnBoy5]

if he is busy they will get him to call you back when hes not. i personal think he loves helping. he asked me when i was having a problem if i had a diagnostic scan tool and i was like well i just happen to have a snap on modis. he was shocked as i am not a shop. but i think that started the excitement for him, i hooked the scan tool up and he KNEW THE MENUS BY HEART. that really impressed me. we then proceed to do a drive test and i was reading off reading while i did different thing to the truck driving and he told me ok go home and do these things. it was a few different things and BAM the problem was fixed. I love calling up there because they are so nice and helpful also dave usually has a cool story to tell about something!

 

[ttbird]

WilsonF, got it correct. 94's and 95's have 47rh's. I have a 95.