45RFE trans

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66dartman

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My friend's 99 grand cherokee 4.7/45RFE has recurring "wrong ratio 4th " codes and has gone into a hard shifting, limp home mode. Nothing in the pan, fluid looks clean and does not smell burnt. We are planning to pull it out, any pitfalls I need to know about on these tranny's? this will be my first one.
Thanks in advance.
 
when trans is put back together,have it standing upright so the thrust washers in input assembly stay in place because they can easily move
 
Before you pull it out .. what's the mileage on the vehicle, and what are the PO codes stored in the TCM or PCM?
 
A very common failure item are the input and/or output speed sensors. On the WJ vehicle, I'm pretty sure input and output are the same sensor (same part number).

At any rate, on this vehicle to check the sensors it's easier to remove them from the trans. The input sensor is closest to the front of the vehicle, and the output towards the rear. Both sensors are on the drivers side of the trans, and both should have a black 2-pin connector. Remove them and simply check the sensor for continuity. If the sensor reads open (no resistance), it's bad.

I once replaced an output speed sensor on a 45RFE, only to have the input speed sensor fail a month later, so now I encourage my customer's to just replace both--they can fail that often.

If you're in need of new sensors, you'll want to use OEM sensors, from the dealer. (I'm guessing 50-60 bucks each).

Not sure if this is the problem or not (am interested to know the exact PO codes stored) but figured we'd start you off with the most common things first.

Oh and no charge on the diagnostic time .... :-D :toothy10:
 
Thanks for the replies. Chris, it has about 120,000 on it. My friend bought it used, but he does not tow with it. I did not write the codes down (stupid, I know), but on the ford trans when you get the wrong ratio codes it usually means slippage. I have not been around these 45rfe trans at all. I am going out of town and will be back next week. I will get the codes back out of it and let you know. would rather put speed sensors in it for sure.
 
Isn't there something different on the 45re than let's say the 46re,48 etc..?

Something about the valve body being made differently?
 
Just to narrow it down a little, if the speedometer isn't working along with the limp-in-mode, it's the output speed sensor. Just replaced one in my wife's 96 3.8L Grand Caravan ES. with 225K miles and still going strong.
 
The 45rfe is kind of based off a caravan (604) trans. The 42re,44re are based off a 904 and the 46re is based off a 727
 
mod38-1 said:
The 45rfe is kind of based off a caravan (604) trans. The 42re,44re are based off a 904 and the 46re is based off a 727
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I have a 03 Dodge Ram with the 46re and afraid it's going to die on me at any minute. The truck only has 45k on it but I have heard some nasty things about this transmission. The 45 is in the trucks with the Hemi motor mine was the last of the 360. I of course didn't know of the transmission issues until I bought it.
 
The 45RFE isn't really based off of a fwd transaxle. The 42RLE (Jeep Liberty and some Dodge trucks '03 and up I believe)is however, based off of the front drive 604 transaxle.

These newer transmissions and transaxles are electronically shifted, and
electronically governed (something we are not used with our old-school 727/904). So you'll want to plug in your scanner, check for codes and view some data stream before tearing down the unit.

Just my 2 cents .. great info on this thread guys.

Jeff call me anytime if you need help on that '99 WJ, brother. That's all I used to work on at the Jeep dealer. :toothy10:
 
What I meant by that was it has a input clutch assembly and no bands,.Also has 2 sets of clutches in case
 
Duster346 said:
These newer transmissions and transaxles are electronically shifted, and
electronically governed (something we are not used with our old-school 727/904).
Click to expand...


That what it was ... elctronically shifed. You can't install a shift kit on those valve bodies right?
 
mullinax95 said:
That what it was ... elctronically shifed. You can't install a shift kit on those valve bodies right?
Click to expand...

Actually do they do have shift kits for them. Trans-go makes them. In addition to that my Superchips tuner in the perf. or towing mode makes it shift firmer than stock. Just by reprogramming it with the tuner it now gets a little 2nd gear scratch. I imagine with the Trans-go kit it'd be comparable to a torqueflite but that's just a guess.
 
There is one other possibility. The ECM, as I understand it (for the Rams) compares the RPMs of the input and output sensors, as well as the sensor on the rear axle housing (reading the ring gear). If the rear axle sensor is faulty, it could cause the same symptoms, since the system is not seeing proper RPMs when compared to each other.
 
fishy68 said:
Actually do they do have shift kits for them. Trans-go makes them. In addition to that my Superchips tuner in the perf. or towing mode makes it shift firmer than stock. Just by reprogramming it with the tuner it now gets a little 2nd gear scratch. I imagine with the Trans-go kit it'd be comparable to a torqueflite but that's just a guess.
Click to expand...

Yeah I know that they have the SC but back years ago when we (me and the guys on DodgeTalk.com) was talking about kits no one didn't have a kit for the 45fre. I guess Trans-go finally made one. I put a performance valve body in my 46re and it seems it is shifting harder than it ever has. I reset the ECM but it still hits pretty hard. I believe you and I talked about it before.
 
Just a followup.... I checked the input and output sensors which are on the driverside of the trans and the input sensor was open, no resistance. Replaced both sensors a week ago and he has had no issues. Thanks again Chris, your diagnosis was right on.
 
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