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TRANSMISSION IN?LIMP? MODE

Tiny
BOBSCNC
  • MEMBER
  • 2001 DODGE CARAVAN
Transmission problem
2001 Dodge Caravan Two Wheel Drive Automatic 101187 miles

The symptons are: When you turn key onand it does the little thing to check all dash lights. It gets to the point where it turns all the boxes around the P R N D etc. They should go out but all the boxes stay lite.
Rev and one of the FWD gears work but it does not shift up or down. The speedometer and odeometer do not move or change. Tach and all other gauge seem to work OK. The dealer I bought it from did a diagnostic scan. It returned something about the data link was bad to transmission.



Another mechanic said that the output speed sensor was the problem. Changed that NO HELP.
He suggested the input speed sensor next. Changed that NO DIFFERENCE.

I am at wits end here.

some thing to add: I noticed that the check engine light WAS NOT on when I test drove it after changing sensor I have a $15 donation from another unrelated elect problem. That turned out to be a weak 40A circiuit breaker just for info.
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Wednesday, April 8th, 2009 AT 11:46 AM

35 Replies

Tiny
BMRFIXIT
  • MECHANIC
  • 19,053 POSTS
Locate TCM and check wiring harness
check yellow wire for power when key on or engine running
the TCM is located behind the inner

fender well of the driver side wheel. It has a very high failure rate due to corrosion
check wiring harness
let me know
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Friday, August 18th, 2017 AT 8:17 PM
Tiny
BOBSCNC
  • MEMBER
  • 10 POSTS
I found the the input shaft speed sensor to be bad thanks for this post cost me $43.00 to fix it.
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Friday, August 18th, 2017 AT 8:18 PM
Tiny
BOBSCNC
  • MEMBER
  • 10 POSTS
I removed the connector from theTCM checked the yellow wire, there is 0 Volts present with the key in run position.
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Friday, August 18th, 2017 AT 8:18 PM
Tiny
BMRFIXIT
  • MECHANIC
  • 19,053 POSTS
Check fuses
check for a short in the wire
go back about a foot and check for power
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Friday, August 18th, 2017 AT 8:18 PM
Tiny
BOBSCNC
  • MEMBER
  • 10 POSTS
Where does this Yellow wire go to from the TCM? What is the next place it connects to something?

All fuses are good.
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Friday, August 18th, 2017 AT 8:18 PM
Tiny
BMRFIXIT
  • MECHANIC
  • 19,053 POSTS
Fuse box than ignition switch


https://www.2carpros.com/forum/automotive_pictures/99387_Graphic1_298.jpg



https://www.2carpros.com/forum/automotive_pictures/99387_Untitledtt_1.jpg

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Friday, August 18th, 2017 AT 8:18 PM
Tiny
BOBSCNC
  • MEMBER
  • 10 POSTS
Thanks for the responce. I will track and check the wire in a couple of hours. It is only 30 DEG out side.
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Friday, August 18th, 2017 AT 8:18 PM
Tiny
BMRFIXIT
  • MECHANIC
  • 19,053 POSTS
Make sure you check the wire under the fender and under the fuse box
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Friday, August 18th, 2017 AT 8:18 PM
Tiny
BOBSCNC
  • MEMBER
  • 10 POSTS
Here it is 4 PM central time In wisconsin.

I was tracking the yellow Wir with out much success.

I studied the schematics again and came to some conclusions.

Not trying to start a disagreement but here are some of my thoughts / questions.

I am useing Mitchel schematics from Eautorepair. Com which apears to be the ones you use.

Looking a t schematic POWER DISTRIBUTION CIRCUIT (2OF 3) from mitchel,
and doing a test of the ignition switch
The Yellow wire is only hot (energized) when the switch is in the 'START' position. The pink/white wire is hot in the run position.
Some of the schematics show a connection between the run and start connection but I think that is only there with the key in the start position and not in the run position.

Are we sure that we want to be chasing the yellow wire.
I have the front tire and splash panel back on If the eweather is nice I whill pull it back off andt check the yellow and the pink and white.

Have a good easter and will catch you later.

Bob
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Friday, August 18th, 2017 AT 8:18 PM
Tiny
BMRFIXIT
  • MECHANIC
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Happy easter to you too and to all

so many wires and so many colors
Yellow and red wire should have power at all time
yellow should have power with key on and starting
if not very common for a harness to fail under the fender or around the fuse box
if all ok suspect bad TCM

good luck
let me know monday
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Friday, August 18th, 2017 AT 8:18 PM
Tiny
OBXAUTOMEDIC
  • MECHANIC
  • 3,711 POSTS
Hello,

I have found that 9 out of 10 times with Dodge it is the TCM. The last Dodge with your symptoms that I worked on it ended up being either the Input or the Output Sensors, I say that because I usually just replace both since they are so inexpensive and pretty easy to change, and that fixed the problem. And since you have already change them I would say that it is your TCM.

.
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Friday, August 18th, 2017 AT 8:18 PM
Tiny
BOBSCNC
  • MEMBER
  • 10 POSTS
Any Idea of what they cost?

Have to check scrap yards and look for one that has been rear ended.

Bob
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Friday, August 18th, 2017 AT 8:18 PM
Tiny
OBXAUTOMEDIC
  • MECHANIC
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Hi Bob.

Here in my area I have been able to get them for around $250 from the dealer.

.
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Friday, August 18th, 2017 AT 8:18 PM
Tiny
BOBSCNC
  • MEMBER
  • 10 POSTS
From tests on the the wires I believe it is the TCM also.

I have read somewhere or heard from some one that if I change the TCM The speedometer has to be recalibrated and possible some other things done with the computer?

Can you fill me in on that?
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Friday, August 18th, 2017 AT 8:18 PM
Tiny
OBXAUTOMEDIC
  • MECHANIC
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I don't think the Speedometer will need recalibrating, the only thing is you will need to have the dealer program the TCM.

.
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Friday, August 18th, 2017 AT 8:18 PM
Tiny
BOBSCNC
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I just installed a different TCM. It failed the power on diagnostic just like the other one. ( What happens is when the key is turned on and all the inst cluster lights come on and off but all the boxes around the gear position letters stay on.

So I no longer think that the TCM is the problem.

I have discoverd something new. The ASD relay is clicking of and on at a rapid pace. I think that ASD stands for Auto Shut Down. Is that correct?

It is very quite. I was going to put the starter relay in the IPM, I happened to feel a vibration and when I listened I could hear it.

I am checking the schematics but in the mean time maybe you might know if or how the ASD relay could figure into this

Bob
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Friday, August 18th, 2017 AT 8:18 PM
Tiny
BMRFIXIT
  • MECHANIC
  • 19,053 POSTS
Wiring wirng wiring
check it out
I am all against replacing parts with out checking 1st
Need a tool or a tester CHECK IT @
https://www.2carpros.com/affiliate/uid/bmrfixit_1
need manual CHECK IT @
https://www.2carpros.com/kpages/auto_repair_manuals.htm
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Friday, August 18th, 2017 AT 8:18 PM
Tiny
LSOTO
  • MEMBER
  • 4 POSTS
  • 2001 DODGE CARAVAN
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 162,000 MILES
I"m getting aP1684 and the evil P0700 codes only. I retrieved the codes from the ignition turning method. I'm not too concerned about the 1684 code. My concern is the p0700 code. I have only replaced the input speed sensor- nothing. The strange part is the limp mode is on-off. I can go to work with the mode on, then return without the mode. I can let the van sit for a day or two-- no mode-- go somewhere turn the engine off-- mode is on. I'm thinking the TCM is bad or could this be a wiring issue or output sensor issue. I'm low on funds so I'm trying to avoid repair shops.
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Friday, June 26th, 2020 AT 1:01 PM (Merged)
Tiny
CH112063
  • MECHANIC
  • 1,320 POSTS
You've replaced the input sensor, and your not sure of the next move and no money to repair. I certainly understand your dilema. Why not do this, check the fluid, and if its clean, and is not burnt, you may find a shop thay can scan just the transmission Control Module, some auto stores and repair shops have a scanner that can do this. I believe you have scanned the powertrain module, the TCM has its own codes. It may just need servicing, a fuse could be out. Why not read up on this problem on the website. It explains everthing. Plus they have all the information regarding checking out all the things you may need. There are many reasons for limp-in. I would try to make sure the fluids ok first, the check the trans codes. Your PCM is telling you what you already know. Does it ever not drop into limp in? Does it have 3rd speed in 'D' or the other forward selrctions? Other than OD?
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Friday, June 26th, 2020 AT 1:01 PM (Merged)
Tiny
LSOTO
  • MEMBER
  • 4 POSTS
Thanks for the reply. It has done a limp-in mode before while driving but mostly on starting the van. I do get 3rd gear in which all appears fine but the code is still there. This week all the codes did clear out only to return. I was clearing the codes by removing the pos and neg battery which had limited results in clearing the limp-on
I've been looking around this site for repair tips. I did go to a tran shop today. I think it was BS. After doing a basic check, they said replace TCM. This is without having done a full diagnois which they wanted $85 to do the full diagnois.
Looks like I might have to go to the dealership and pay for a full diagnois.
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Friday, June 26th, 2020 AT 1:01 PM (Merged)

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