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bhdiscgolf 01-09-2013 04:44 PM

2003 Grand Cherokee Transmission issues
I have a 2003 Grand Cherokee Larado V8 which appears to have a Quadra Trac II transmission.

The main issue is that the transmission seems to be slipping in and out of OD when in high gear (speeds 55-75). What is noticed is that the RPM gauge jumps about 300 RPM and then drops right in back intermittently. Usually when going these speeds the RPM ranges from 2000 to 2200 normal.

This oddily happens mostly during the winter time for the past cpl of years, whereas during the warmer weather there seems to be no issues, although I haven't taken it on any long type journeys. Basically I drive it to and from the Lake which is about 40 minutes each direction with boat in tow.

The other thing is the engine races a lot when starting from cold. Maybe and idle issue, or something causing it to make things seem alittle rough.

The following has been done. (Complete tune-up, including all mini hoses replaced, gas filter replacement). (Tranny was serviced under normal circumatances with no issues found at 85,000). (Electrical checked, bad ground from battery negative fixed, alternator is fine).

Also on occasion the transmission seems to forget what gear its in when coasting along with no pressure on the gas pedal and will sometimes kick itself down.

What I can do is feed whoever wishes to help out precisely what I've documented, and why I'm somewhat fearful to take it to a transmission shop before doing do diligence ahead of time.

Thats for any and all assistance.

Brian :)

bhdiscgolf 01-09-2013 04:51 PM

Re: 2003 Grand Cherokee Transmission issues
I forgot to mention that last winter the engine light came on and apparently we have a problem with the TPS. It was replaced, one thing was the mechanic whom I didn't totally trust was measuring the voltage to the TPS and said its not reading correctly. In the previous post I mentioned the ground being replaced for the negative battery cable, and the alternator is functioning properly, no shorts have been found. This main have some importance, but the main thing is the tranny coming in and out of OD.

Frango100 01-10-2013 02:02 AM

Re: 2003 Grand Cherokee Transmission issues
Just to make things straight, the transmission is a 5-45RFE, the quadra trac II has to do with the T-case, which is a NV247.
The symptoms you mentioned in the first post did me think about the TPS sensor.
When the TPS is getting bad, you normally get a hunting rpm, a tranny which gives problems with the shifts or harsh shifts and eventually as well a torque converter unlock (this is probably the rpm jump you see)
Was the TPS replaced by an OEM part from MOPAR? Paralel market stuff can give funny symptoms sometimes.

bhdiscgolf 01-10-2013 12:00 PM

Re: 2003 Grand Cherokee Transmission issues
Thanks for the info on the tranny itself, Ill keep that info in a notepad for future.

As for the TPS, early last year it was causing the Engine light to come on, then it went off for awhile and returned.

We were on a trip at the time and ended up parking the Jeep in a Airport parking lot and getting a rental car for a cpl days, after returning I took it to Advance and they recommended I take it down to a repair shop and have them replace the TPS.

The repair shop installed a new one, (unknown as to whether its a mopar part or not, wish I knew). However the guy screwing around with fixing it told his boss that the wiring was not registering voltage or it was low amps.

We were able to get it back home, and I took it easy on it, now and then the RPM jumps would occur.

During the summertime never and issue, during the winter it becomes major. I took it to another person in town to check the alternator, he had to replace the battery ground cable, rechecked the alternator, everything fine.

However I've suspected something isn't right and making sure my vehicle is getting the right voltage has been my main concern, before jumping to conclusions that the tranny solenoids are bad. Kinda dumb to fix something when you have other issues.

When the guy that replaced the TPS mentioned a voltage reading issue, they told me that Jeep wanted to replace the entire electrical harness system, and I said, put the car back together and it better run and didn't buy into it because they wanted over $1000 to replace the harness + labor.

Any info in how to check this would be fantastic and appreciated. The engine light has not come back on as of yet, but the RPM issue continues to plague the vehicle and my own peace of mind.

Frango100 01-10-2013 12:42 PM

Re: 2003 Grand Cherokee Transmission issues
The voltage problem was that the from the TPS? The TPS gets 5 V from the PCM and shares that together with the crank position sensor, the cam position sensor and the manifold absolute pressure sensor. Any one of those sensors bad could bring the 5 V supply down and prevent the engine from operating.
It would be interresting to see if the 5 V supply is a steady 5 V or not. You can measure that on the connector from the TPS, point 1 to ground, with the ignition switched on but engine not running.
A rough idle by the way many times is caused by a dirty idle air control motor plunjer and air passage in the throttle body. Do you know if this was cleaned? Has nothing to do with the transmission problem you have though. Did you have these same problems before changing the TPS sensor? If not, i would put an original MOPAR part in there, just 2 torqx screws and 1 connector.

bhdiscgolf 01-10-2013 01:12 PM

Re: 2003 Grand Cherokee Transmission issues
Not sure on the idle air control plunger, will get that checked out.

Basically when I start it up, the engine wants to rev up some and drop, then rev up and drop, but its going up to like 1600 RPM and dropping back to 1000 which is far more than I would expect it to do, takes about 20/30 seconds to mellow out some, but stills wants to climb from then 900 to 1200. Takes way to long before it becomes steady at around 900.

I think what Ill do is see about finding out whether the TPS is Mopar or someone else s brand. Ill also get the voltage checked and see if we can rule out the TPS or if its been the culprit the whole time.

The TPS came on 2 or 3 times, I had it reset before I understood what it was and finally got it replaced, this was over about 3 months, seems that it doesn't just come back on after resetting very quickly, takes awhile, which tends to lead me to getting the voltage checked.

Thanks again, Ill keep you updated.

Frango100 01-10-2013 03:25 PM

Re: 2003 Grand Cherokee Transmission issues
When the idle air control motor plunjer is dirty, the rpm hunts up and down, but normally not that high. Also 900 rpm for steady idle is too high, it should normally be 650 rpm.

bhdiscgolf 01-10-2013 04:08 PM

Re: 2003 Grand Cherokee Transmission issues
Yes I agree, here is what I did today, unable to complete the task, wasn't sure about something so I stopped and backed off.

1. Started the engine, rev'd up for a short bit like before but then settled back down, rpm went down to 750 but returned to around 900, maybe needs adjustment not sure.

2. Turned off the engine.

3. Unhooked the housing going from the Air Filter to the large cover over the top of the engine.

4. Unhooked the 2 side bolts from the top and loosened the clamp on the back to remove the large top blocking everything from full viewing.

5. Unable to get the large top to free itself from the back mount where I had loosened the clamp, wasn't sure if I should try forcing it off so I stopped.

6. I did notice to Electrical Units on top of each other though looking in from the right side of the engine.

7. I think the top unit is in fact the TPS, but not sure. However the TPS has 3 holes for hold wires going in, only the 1st and 2nd holes had wires in it, one orange the other red, no wire in the 3rd hole. Wasn't sure why that was.

8. Unable to determine if its a Mopar OEM unit.

Any suggestions ? I'm trying trust me, but being careful. I also read 2 other articles that described almost precisely what I have to you thus far, both where the idle was going up and down, and how the RPM guage would jump 300 RPM when in OD. Both required the TPS to be removed. I'm suspecting the new Unit may be in place but is malfunctioning do to how it was installed, not sure.


Frango100 01-10-2013 04:56 PM

Re: 2003 Grand Cherokee Transmission issues
The 2 units on the left side of the throttle body ( i always use the drivers position to indicate where what is) are indeed the TPS on top, and the idle air control motor below it.
There should be 3 wires going to the TPS connector when iīm not wrong, 1 for the 5 V supply, one for the sensor ground and one for the throttle position sensor signal.
The color code should be Orange for the 5 V supply, Orange with a Red stripe for the position sensor signal and Black with light Blue stripe for the sensor ground.
I will confirm this on my jeep now.

Frango100 01-10-2013 05:03 PM

Re: 2003 Grand Cherokee Transmission issues
Yes, just checked it on my jeep and the color coding is indeed as i had written down with 3 wires going to the connector. If you only have 2 wires, then there is something wrong and i donīt know how it can be working like that.
It seems that the sensor ground wire is missing on yours. Maybe that it can find its ground via the sensor housing, but thats not the way its suppost to be. When you follow the wire bundle, is there not a loose wire somewhere?

bhdiscgolf 01-10-2013 05:50 PM

Re: 2003 Grand Cherokee Transmission issues
I'm not sure about there being a 3rd black wire, I didn't directly notice any wire just hanging lose, and not sure how the 2 wires we already both agree on are actually attached, mainly because I'm not sure how the Unit functionally works because I couldn't fully uncover and view it.

Coming out of the harness are 2 wiring segments, one with 2 wires only going to the TPS, and a group going to the idle air control unit.

The only thing I can do at this point is peel back the tape from the harness itself and see if I can find a missing wire, perhaps broken off, as I mentioned when they pointed to a voltage problem and said I needed to get the entire harness unit from Jeep we were talking a lot of money, not only for the harness, but the labor, I'm sure it would have been upwards of 1200.00 or more.

I will take the time tomorrow morning and trace it out as best I can, and I think there is a person I might be able to take it to and check it out, I wonder also if the ground is missing if that would create and issue for the Engine light not to come on and redisplay the error code again, not sure, but a thought.

Like I said I will let you know in the morning for sure.


Frango100 01-10-2013 06:51 PM

Re: 2003 Grand Cherokee Transmission issues
In worst case when you couldnīt find the wire, you could run a paralel wire to the bundle. It goes from the TPS connector back to the PCM connector C1 point 4.

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