Speed Input/Output Sensor failure...

**Double E** · 05-23-2008, 09:27 AM

Wife calls on the way to work this morning describing the same symptoms as when a speed sensor went bad a few years ago. (I do not know which one of the 2 failed though.)

I had her pull the codes (she’s a good listener) and PO700 is the only one that appears. From her description, it’s “slipping” and acting like she’s “hitting potholes” every so often. (Classic speed input sensor failure description).

Local dealer has the part and I just need to pick it up later today. (part# 4799061AB)

There are 2 speed input sensors on the Jeep and I’m working with the theory that only one is bad.

Do any of you have a recommendation as to which one is more likely to have failed?

Is there a way to use a multi-meter to test it while it’s still mounted?

Also, do you have an idea as to how much tranny fluid is going to come out when I remove/replace the sensor?

Thanks in advance…

JG_Canuck · 05-23-2008, 10:57 AM

On the 545RFE the sensors are identical, so trial and error is your friend. Replace one, if it doesn't fix it, swap out the other...

I replaced the input sensor on mine, and NO fluid leaked out.

**Double E** · 05-23-2008, 02:11 PM

Cool...thanks for the fast note back. I just picked up the part & am replacing in a few mins ...after I crack a cold one.

I still have the first one that went bad so maybe I'll test it to see if there's a resistance difference compared to new.

**Double E** · 05-24-2008, 11:19 AM

Update: Fixed!
Of the two, the one that was still the original tested bad.

I also tested the one that had been declared "bad" a few years ago. It registered "open" when the ohmmeter was put on the contacts.

The new (good) one registered steady .54 Ohm when the multimeter leads were applied to the contacts and wildly fluctuated when a magnet was brought close.

The bad one I pulled out today also registered as "open".

The jeep ran great after the swap to a good one.
The old and new do have some minor physical differences.

Took all of 20 minutes to replace & (literally) only a drop of tranny fluid came out.

Thanks wjjeeps.com for the how-to, talent and guts to do it myself. Saved well over $100 in time/labor/materials/headache.

JG_Canuck · 05-25-2008, 01:21 PM

I figured it was probably the one that wasn't previously replaced. Good to hear that you got it fixed.

It really is an easy repair. Just don't try it without letting the exahust cool first...

JayIV · 05-25-2008, 02:10 PM

How many sensors does the 545 have, and where is a list of the symptoms when one goes out?

JG_Canuck · 05-25-2008, 06:12 PM

Two. Input and Output.

Transmission usually goes into limp mode. Hard/erratic shifting. Generic P0700 fault code on the odometer.

4LOW1994 · 03-14-2013, 12:43 AM

My 1994 ZJ seems to have the same symptoms for the sensor failure.

my jeep doesn't want to get out of first and when it does get into second it doesn't want to stay and it jumps back down to first again to early.

it honestly feels like its going in to neutral and the RPMs go through the roof.

im a poor college student and this car is my daily driver so i need it working.

i just need to know if this is something i can fix myself or if its to complicated... i also need to know if its a sensor failure or if im mistaken and it is something else.

HELP!

**ratmonkey** · 03-14-2013, 08:54 AM

Quote:

Originally Posted by 4LOW1994

My 1994 ZJ seems to have the same symptoms for the sensor failure.

my jeep doesn't want to get out of first and when it does get into second it doesn't want to stay and it jumps back down to first again to early.

it honestly feels like its going in to neutral and the RPMs go through the roof.

im a poor college student and this car is my daily driver so i need it working.

i just need to know if this is something i can fix myself or if its to complicated... i also need to know if its a sensor failure or if im mistaken and it is something else.

HELP!

You have a completely different transmission.
Yours could be a number of things. Any codes? Use the "key trick" and count the od off light flashes.

4LOW1994 · 03-14-2013, 01:10 PM

I did the key trick multiple times and each time i got the signal 55 for "end code" but nothing before that so i have no idea what to do...

**ratmonkey** · 03-14-2013, 02:00 PM

you could have a band worn out or the apply strut dropped out, the throttle valve cable may need adjusted, the front servo may be broken, you may have a plugged up governor sensor and solenoid or plugged up filter, you could be low on fluids. there's a pretty long list of things that can cause that. start with the tv cable and fluid check. if it's never been changed i'd drop the pan next and see what you find in there falling out.