Limp mode

Tiny
SLIMONTIME
  • 2004 DODGE STRATUS
  • 2.4L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 165,000 MILES

Even after replacing the TCM, most sensors, gone through all relevant wiring, found and cleaned the the main grounds checked all fuses and relays, reset codes. Said three hail Mary's, she just will not shift! Little help? I feel that it is something basic I have overlooked. Engine runs fine, starts well. Maybe a stray sensor I just cannot find the issue.

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Sunday, May 21st, 2017 AT 12:17 PM

23 Replies

Tiny
2CARPROS KEN
  • ADMIN
  • 7,797 POSTS

Hello,

It sound like the transmission relay is not working for some reason. Here is a wiring diagram (BELOW) and a guide to ehlp you do some testing.

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

and

https://www.2carpros.com/articles/how-to-check-wiring

Please run some tests and get back to us so we can continue helping you.

Cheers, Ken

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Wednesday, May 24th, 2017 AT 1:08 PM
Tiny
SLIMONTIME
  • MEMBER

Well I did the tran relay testing. I have 12v down to the solenoid. There are no shorts that I can tell. Wiring is quite good. I cant test the pcm but am still cautious for changing it out. It just wont "talk" to that one relay. The solenoid hence is always in "limp". Could just this one thing fry the pcm? Opinions please.

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Thursday, May 25th, 2017 AT 1:08 PM
Tiny
2CARPROS KEN
  • ADMIN
  • 7,797 POSTS

Hello,

Yes the computer can be bad not triggering the relay. Can you run the codes to see if anything comes up?

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Please run this test and get back to us so we can continue helping you.

Cheers, Ken

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Thursday, May 25th, 2017 AT 9:03 PM
Tiny
SLIMONTIME
  • MEMBER

Po888 causing p700. I have diligently performed all wire and harness checks allok. Pcm will not talk to relay, relays good. I think its the pcm shotout. Unless you have a fresh idea. There's nothing left.

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Thursday, May 25th, 2017 AT 11:44 PM
Tiny
2CARPROS KEN
  • ADMIN
  • 7,797 POSTS

Yep it sounds like it.

Please let us know what happens, I am interested too see what it is.

Cheers, Ken

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Friday, May 26th, 2017 AT 1:53 PM
Tiny
SLIMONTIME
  • MEMBER

Yup, I switched out the PCM with a same yr. Model and engine from boneyard. I wish I had pinned it there a month andf $400 ago LOL. Bye.

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Monday, May 29th, 2017 AT 10:01 AM
Tiny
2CARPROS KEN
  • ADMIN
  • 7,797 POSTS

Glad you could get it fixed, that kind of problem can be tough. Please use 2CarPros anytime we are here to help

Cheers, Ken

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Monday, May 29th, 2017 AT 12:20 PM
Tiny
SAVANNAHSULWER
  • 2002 DODGE STRATUS
  • 3.0L
  • V6
  • 2WD
  • AUTOMATIC
  • 180 MILES

Obd2 code p0720 with reported fix from oreilly scanner of replacing transmission speed sensor and that is after replacing both sensors. Had codes saying all gears werent working right before and speedometer about 20 miles off, when going 60 it says im going 90. Now the speedometer doesn't work at all and its still in limp mode after about 60 seconds of driving but I can manually down shift to 1 and 2 when before I couldn't. Still can't drive home in this condition even if I limped it at 50 MPH I think that would hurt the transmission being stuck in 3rd for a 2 hr drive. The transmission fluid does smell burnt. I just bought this car. I want to flush it, but if I'm going to have to replace the transmission I might as well wait. Can the car tell the fluid is spent and that is why its throwing a code and still going in limp mode? May sound silly but no one has been able to give me a definite answer on the fluid being the problem. Thank you in advance

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Monday, May 29th, 2017 AT 12:21 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • EXPERT
  • 68,289 POSTS

The computer doesn't recognize the condition of the trans fluid. So, that isn't the cause. Most likely, a flush isn't going to help. Is that the only code that has shown up?

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Monday, May 29th, 2017 AT 12:21 PM (Merged)
Tiny
SAVANNAHSULWER
  • MEMBER

Okay good thanks for the info on the computer not knowing the condition of the trans fluid. Yes as of now thats the only code, the code says to change the speed sensor even thought thats what I changed? I'm thinking maybe the wires need to be swapped too but they look good and aren't touching any hot places.

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Monday, May 29th, 2017 AT 12:21 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • EXPERT
  • 68,289 POSTS

Now that the sensor is changed, is the speedo working properly?

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Monday, May 29th, 2017 AT 12:21 PM (Merged)
Tiny
SAVANNAHSULWER
  • MEMBER

The speedometer doesn't work at all now that I changed them. But I can manually down shift now, but still in limp mode and can't go into 4th. I swapped them back and the speedometer is back to being 20-30 mph over the actual speed.

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Monday, May 29th, 2017 AT 12:21 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • EXPERT
  • 68,289 POSTS

Try a different speed sensor. You may have gotten a bad one.

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Monday, May 29th, 2017 AT 12:21 PM (Merged)
Tiny
DREWVIN00
  • 1995 DODGE STRATUS
  • 4 CYL
  • FWD
  • AUTOMATIC
  • 169,700 MILES

95 stratus going into limp mode, tranny shop said nothing wrong, but still doing it. Is this a sensor or what. It runs fine one day then not so good the next.

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Monday, May 29th, 2017 AT 12:21 PM (Merged)
Tiny
CARADIODOC
  • EXPERT
  • 28,246 POSTS

As a general rule, if it goes right to second gear as soon as you shift into gear, the problem is sensor-related. If it goes to limp-in during or right after an up-shift, it is more likely to be slippage in one of the clutch packs.

Either way, there will be a diagnostic fault code stored in the Transmission Computer. You'll need to find a mechanic with a scanner that can access that computer to read the code(s). That will give you an idea of what's happening. Don't disconnect the battery before those codes are read or that valuable information will be lost.

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Monday, May 29th, 2017 AT 12:21 PM (Merged)
Tiny
DREWVIN00
  • MEMBER

It seems to go into limp mode right after upshifting or coasting between 35 and 40mph. You guys are great, I'm on disability and was hoping it was something I could fix myself if you have anything else let me know. Thanks alot

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Monday, May 29th, 2017 AT 12:21 PM (Merged)
Tiny
CARADIODOC
  • EXPERT
  • 28,246 POSTS

You probably figured out that to get it out of limp mode you have to turn the ignition switch off and restart the engine. If it really is slippage in a clutch pack, you might be able to overcome it for a while by accelerating past the shift point, then letting up on the gas until it up-shifts and locks solidly into gear. What I mean is, suppose it always defaults to limp mode when shifting from second to third gear. If it likes to shift into third at, ... Oh, ... Say 30 mph, accelerate a little harder than than normal so it stays in second until 40 mph, then let off the gas to force it to up-shift to third. There won't be any torque on the clutch pack so it will have less tendency to slip.

That slippage is detected by comparing the input speed sensor's reading to that of the output speed sensor. When the two don't match for the specific gear ratio, it goes to limp mode.

You can also get an idea of the amount of clutch plate wear by viewing the "clutch volume index", (CVI). That is a set of four numbers that correspond to the number of ccs of fluid it takes to apply each clutch pack. An experienced transmission specialist can tell you what's normal and how much life can be expected yet. The problem is the computer constantly updates its shift schedules to overcome that normal wear and provide crisp shifts, until the day comes when it can't update enough. Years ago we had a year or two of mushy shifts to warn us that wear was taking place. With these computer-controlled transmissions we don't have that warning.

I should mention too that a lot of people think they're going to solve a problem by disconnecting the battery cable to reset something. What that will do is reset the Transmission Computer to the shift schedules programmed in at the factory. It can take a dozen shift cycles or a few miles of driving before the current needs are relearned and the memory is updated. Until that happens it could shift too harshly or it could be too soft and cause slippage. The best approach is to head straight to the transmission specialty shop to have the fault codes read. They might recommend rebuilding the transmission, but since that's what their business is, that's what they're hoping to tell you. Most shops are reputable and will repair rather than rebuild because they want to earn your repeat business, but you should also get a second opinion before committing to an expensive repair. A lot of mechanics are real good with cars but not good at communication skills. They might see from the CVI numbers that your transmission is going to need to be rebuilt very soon, and any other repair would be a short-term band-aid, but they should explain it to you that way. There could be a less expensive problem right now that a second shop fixes after the first shop recommended a rebuild. If you don't know why that first shop went with the expensive route, you'll be left thinking they were trying to rip you off when in reality they were looking at the bigger picture and what's in your best interest in the long run.

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Monday, May 29th, 2017 AT 12:21 PM (Merged)
Tiny
NATEALBRIGHT
  • 2002 DODGE STRATUS
  • 97,000 MILES

I have a 2002 Dodge Stratus that went into limp home mode today. I stopped by AutoZone and got a free diagnostic test. If I provide the codes, can someone please help me understand what I need to do and if the car is safe to drive in the mean time until I can figure out exactly what needs done? The codes I got were p0700 and p0705. Everything I've read so far points to a solenoid, but I would really like some personalized device.

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Monday, May 29th, 2017 AT 12:21 PM (Merged)
Tiny
CARADIODOC
  • EXPERT
  • 28,246 POSTS

P0705 Transmission Range Sensor Circuit malfunction(PRNDL Input)

This refers to the neutral safety switch and would be a relatively inexpensive repair. In general, a switch, speed sensor, or other electrical problem will put the system in limp mode as soon as you shift into drive or reverse. It will stay in second gear to allow you to drive it slowly to a repair shop without needing a tow truck.

If it defaults to limp mode during or right after an up-shift or down-shift, it is usually caused by slippage in one of the clutch packs. That requires a rebuild.

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Monday, May 29th, 2017 AT 12:21 PM (Merged)
Tiny
NATEALBRIGHT
  • MEMBER

Thank you for the quick and timely response. However, I actually had a typo in my question. The code was not P0705 but rather P0755. Any further input would be much appreciated. Thank you!

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Monday, May 29th, 2017 AT 12:21 PM (Merged)

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