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Old 10-09-2011, 11:52 AM
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Possible speed sensor or transmission issue.

I will try to explain this issue as clearly as possible. Over the last week I have noticed that my 99 JGC I6 automatic W/2WD has been shiftin oddly on what I believe to be 1st and MAYBE 2nd gear. When I come to a stop and it is not all of the time it seems that my engine revs up and but is delayed in moving until what feels like the gear catches and it moves. When I first squired the jeep my gears would always change right at 2000-2200 RPM and over the last few months 27-2800 RPM became a little more frequent. When I first noticed this issue I saw that for the first time the RPM went to approx 3200 RPM. When I told my friend who works on cars he said that the Jeeps speed sensor tells the computer when to switch the gear based on speed that the vehicle is traveling and that if the sensor was going bad that could be the cause of my issue. When I am on the highway and im going faster I notice no hesitation, jumping or issue until I start to slow down in that it almost feels like the car is double shifting down twice, once from 2000 RPM and once again at 1700 RPM. My jeep has 168,000 miles on it. Any opinions on this? I thank you all in advance.
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Old 10-09-2011, 12:18 PM
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Re: Possible speed sensor or transmission issue.

Did you get any error codes?

Retrieving codes: Turn the ignition key until the digital odometer displays, repeat three times in succession and then back to "On" (On/Off, On/Off, On/Off, On). At the fourth "On" the odometer will be replaced with codes. If no codes are present then "Done" will appear.

Your problem sounds exactly like mine and I'm thinking it's the Governor Pressure Sensor and the Governor Pressure Solenoid/Transducer. Both should be replaced at the same time. Here's a good example of someone with the problem and pictures of both parts.

http://www.jeepforum.com/forum/f310/42re-p1762-p1763-governor-pressure-sensor-solenoid-write-up-1182260/
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Old 10-09-2011, 12:25 PM
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Re: Possible speed sensor or transmission issue.

Thank you, does it matter that my C.E.L has never came on?

Quote:
Originally Posted by Reichminister Goebbels View Post
Did you get any error codes?

Retrieving codes: Turn the ignition key until the digital odometer displays, repeat three times in succession and then back to "On" (On/Off, On/Off, On/Off, On). At the fourth "On" the odometer will be replaced with codes. If no codes are present then "Done" will appear.

Your problem sounds exactly like mine and I'm thinking it's the Governor Pressure Sensor and the Governor Pressure Solenoid/Transducer. Both should be replaced at the same time. Here's a good example of someone with the problem and pictures of both parts.

http://www.jeepforum.com/forum/f310/42re-p1762-p1763-governor-pressure-sensor-solenoid-write-up-1182260/
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Old 10-09-2011, 12:26 PM
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Re: Possible speed sensor or transmission issue.

Does it matter that my C E L has never came on and that I am not receiving any codes?

Quote:
Originally Posted by Reichminister Goebbels View Post
Did you get any error codes?

Retrieving codes: Turn the ignition key until the digital odometer displays, repeat three times in succession and then back to "On" (On/Off, On/Off, On/Off, On). At the fourth "On" the odometer will be replaced with codes. If no codes are present then "Done" will appear.

Your problem sounds exactly like mine and I'm thinking it's the Governor Pressure Sensor and the Governor Pressure Solenoid/Transducer. Both should be replaced at the same time. Here's a good example of someone with the problem and pictures of both parts.

http://www.jeepforum.com/forum/f310/42re-p1762-p1763-governor-pressure-sensor-solenoid-write-up-1182260/
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Old 10-09-2011, 12:28 PM
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Re: Possible speed sensor or transmission issue.

No error codes at all my friend and no check engine light.
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Old 10-09-2011, 12:34 PM
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Re: Possible speed sensor or transmission issue.

Quote:
Originally Posted by southernfryedyankee View Post
No error codes at all my friend and no check engine light.
From your description I'm certain it would be those 2 but maybe it just hasn't manifested itself enough for the OBD to pick it up. Maybe look into replacing the two in the near future to see if it helps. I'm currently waiting for those parts to come in so I can replace them.
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Old 10-09-2011, 12:36 PM
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Re: Possible speed sensor or transmission issue.

How much did they cost to replace and where did you go to get them? Are you doing the work yourself or having someone else do it?
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Old 10-09-2011, 12:38 PM
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Re: Possible speed sensor or transmission issue.

Well I haven't exactly ordered them yet but apparently you can get them through NAPA if you have one near you. We're having a family friend put them replace them for us. But that link I posted is definitely helpful if you're looking to do it yourself. Also, I'm not to sure how much they cost, maybe anywhere from $50-$100 a piece.
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Old 10-09-2011, 01:56 PM
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Re: Possible speed sensor or transmission issue.

My 99 4.7 laredo did that and it was input/out speed sensor. Parts were $20 apiece at dealer.
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Old 10-09-2011, 02:09 PM
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Re: Possible speed sensor or transmission issue.

Here is what the jeep manual says as probable causes:

1. Fluid Level Low/High. 1. Correct fluid level and check for leaks if low.
2. Fluid Filter Clogged. 2. Replace filter. If filter and fluid contained clutch material or metal particles, an overhaul may be necessary.
3. Throttle Linkage Mis-adjusted. 3. Adjust linkage as described in service section.
4. Throttle Linkage Binding. 4. Check cable for binding. Check for return to closed throttle at transmission.
5. Gearshift Linkage/Cable Mis-adjusted. 5. Adjust linkage/cable as described in service section.
6. Clutch or Servo Failure. 6. Remove valve body and air test clutch, and band servo operation. Disassemble and repair transmission as needed.

7. Governor Circuit Electrical Fault. 7. Test using DRB III
scan tool and repair as required.
8. Front Band Mis-adjusted. 8. Adjust band.

9. Pump Suction Passage Leak. 9. Check for excessive foam on dipstick after normal driving. Check for loose pump bolts, defective gasket. Replace pump



assembly if needed.


Strangely enough the manual doesn't mention the speed sensor as a cause of delayed shifting, but the output speed sensor on the 42RE is used by the TCM and shared with the PCM. On the 5-45RFE i'm sure the input and output speed sensor signals are used to calculate the shift points, for the 42RE i'm not sure.
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Old 10-09-2011, 02:39 PM
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Re: Possible speed sensor or transmission issue.

Another possible cause from what I am reading could also be the throttle position sensor.
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Old 10-09-2011, 02:43 PM
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Re: Possible speed sensor or transmission issue.

Frango that was a good read, When I checked my fluid, it looked higher than what I THOUGHT it should be. Also the car had been running fine for the last 7 months and did not start acting "off" until it got cold at night and I would start the jeep up at 445 to go to work.
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