1999 Jeep Cherokee erratic shifting and engine light
07-04-2017, 11:11 AM
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1999 Jeep Cherokee erratic shifting and engine light
Hi, all,
For the past few weeks, my jeep has been throwing an engine light that seems to be related to a specific event. When I am going downhill in 5th gear and take my foot off the gas, the tach shifts into 4th gear briefly and then back to 5th gear.
Here's a video of what the tach does: https://drive.google.com/open?id=0B4...zZmakNKamxKZ0E
From previous experience, I thought that the engine didn't shift up in this situation, just stayed in 5th gear, but might be wrong. The two times the engine light came on this was exactly the sequence of events. The first time, the codes included an evap warning and two other codes that I can get once I talk to my mechanic. In addition, to this, particularly when in 4th or 5th gear, when I try to accelerate, it seems to hesitate as if it's going to shift and then doesn't shift, or stutters before shifting - this happens when the tach is around 1.9-2k. It's not constant, but happens pretty frequently, particularly past an hour or so of driving.
The mechanic says the transmission is fine and the fluid is where it should be. He replaced the wire harness that goes across the fuel rail since it had melted and might have been shorting out but this didn't fix it. He also replaced the TPS, but this same problem occurred today. He also fixed the right engine mount.
I'm thinking it's another sensor but wanted to ask what you all thought and if it might be a sensor, which ones to look at first.
Thanks for any help.
Details:
1999 Jeep Cherokee Sport 4.0
ETA: Just talked to the mechanic and he recalled the codes being P0121, P0123 or 122, and P0700. Correction, he didn't replace the TPS because it was testing fine.
For the past few weeks, my jeep has been throwing an engine light that seems to be related to a specific event. When I am going downhill in 5th gear and take my foot off the gas, the tach shifts into 4th gear briefly and then back to 5th gear.
Here's a video of what the tach does: https://drive.google.com/open?id=0B4...zZmakNKamxKZ0E
From previous experience, I thought that the engine didn't shift up in this situation, just stayed in 5th gear, but might be wrong. The two times the engine light came on this was exactly the sequence of events. The first time, the codes included an evap warning and two other codes that I can get once I talk to my mechanic. In addition, to this, particularly when in 4th or 5th gear, when I try to accelerate, it seems to hesitate as if it's going to shift and then doesn't shift, or stutters before shifting - this happens when the tach is around 1.9-2k. It's not constant, but happens pretty frequently, particularly past an hour or so of driving.
The mechanic says the transmission is fine and the fluid is where it should be. He replaced the wire harness that goes across the fuel rail since it had melted and might have been shorting out but this didn't fix it. He also replaced the TPS, but this same problem occurred today. He also fixed the right engine mount.
I'm thinking it's another sensor but wanted to ask what you all thought and if it might be a sensor, which ones to look at first.
Thanks for any help.
Details:
1999 Jeep Cherokee Sport 4.0
ETA: Just talked to the mechanic and he recalled the codes being P0121, P0123 or 122, and P0700. Correction, he didn't replace the TPS because it was testing fine.
Last edited by ebranch; 07-04-2017 at 11:27 AM.
07-04-2017, 11:29 AM
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Year: 1999
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With codes, the devil is in the details.
You need to post every code here for comment. Not just a description of the code, but the actual PXXXX codes.
The codes are likely related and code interpretation is NOT always straight forward. Venturing guesses without the codes is just that....guesses.
Post the codes and we'll try to help you sort through it. If your mechanic is not able to resolve the codes, you should get another opinion from a trusted repair shop. Shops that employ ASE Certified Technicians is your best bet as they have been educated to use a "testing based strategy" to get to the root cause.
You need to post every code here for comment. Not just a description of the code, but the actual PXXXX codes.
The codes are likely related and code interpretation is NOT always straight forward. Venturing guesses without the codes is just that....guesses.
Post the codes and we'll try to help you sort through it. If your mechanic is not able to resolve the codes, you should get another opinion from a trusted repair shop. Shops that employ ASE Certified Technicians is your best bet as they have been educated to use a "testing based strategy" to get to the root cause.
Last edited by tjwalker; 07-04-2017 at 11:31 AM.
07-04-2017, 11:40 AM
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Thanks. Sorry, I think I posted my edit with the codes while you were replying. I just talked to the mechanic and he let me know that he recalled the codes as P0121, P0123 or 122, and P0700. He also said that he didn't replace the TPS because it was testing fine.
07-04-2017, 11:50 AM
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Year: 1997
Model: Cherokee
Engine: 4.0L
P0121 - TPS Voltage Does Not Agree With MAP Sensor
P0122 - Throttle Position Sensor Voltage Low
P0123 - Throttle Position Sensor Voltage High
P0700 - Generic transmission fault (this can be caused by the TPS)
Could be a ground or wiring issue. That doesnt rule out the TPS itself tho, even if it is replaced. Mopar is best.
See post #14 to test the TPS. You can use a safety pin to backprobe the connector, but i dont remember what size.
https://www.cherokeeforum.com/f2/thr...e-help-108785/
Check this out too.
P0122 - Throttle Position Sensor Voltage Low
P0123 - Throttle Position Sensor Voltage High
P0700 - Generic transmission fault (this can be caused by the TPS)
Could be a ground or wiring issue. That doesnt rule out the TPS itself tho, even if it is replaced. Mopar is best.
See post #14 to test the TPS. You can use a safety pin to backprobe the connector, but i dont remember what size.
https://www.cherokeeforum.com/f2/thr...e-help-108785/
Check this out too.
Last edited by fb97xj1; 07-04-2017 at 11:53 AM.
07-05-2017, 05:49 AM
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Year: 1997
Engine: 4.0
the jeep will briefly unlock the torque converter when coasting like that and letting off the throttle. i assume you're seeing the spike in rpm when you reapply throttle? if so, that's normal. also, the aw4 has 4 gears. the torque converter locking up may seem like a 5th.
does it only act like that when letting off the gas? does it drive fine otherwise?
does it only act like that when letting off the gas? does it drive fine otherwise?
07-05-2017, 06:29 AM
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Oh, ok. The tach goes up when I let my foot off the gas. So you see the tach fall initially when I take my foot off the gas, then go up on its own, then fall on its own, then go up when I put my foot on the gas at the end
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07-07-2017, 04:21 PM
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Alright, I'm not getting any luck with this. I'm going to test out the TPS tonight, but now it's just stalling when I come to a stop. I think this is an electrical problem and have now sunk a good amount of money into not getting it fixed.
Anyone know of a wizard Jeep mechanic in the New York City area? I don't know of anyone in Manhattan and have had nothing but bad luck and really expensive bills here, so anyone know of a shop they trust and have used on Long Island, Westchester, Queens, Brooklyn, Bronx etc.?
Anyone know of a wizard Jeep mechanic in the New York City area? I don't know of anyone in Manhattan and have had nothing but bad luck and really expensive bills here, so anyone know of a shop they trust and have used on Long Island, Westchester, Queens, Brooklyn, Bronx etc.?