2014 Dodge Grand Caravan Trans Control Relay

Kyle Diagnostician Pennsylvania Posted   Latest  
Unsolved
Electrical
2014 Dodge Grand Caravan SE 3.6L (G ERB Gas) 6-spd (62TE)
P0882 — TCM Power Input Signal Low
Intermittent Limp Mode Activation When Codes Set
Various Shift Solenoid Codes

This vehicle goes into limp mode when the code sets. The fault occurs very intermittently. We scoped the trans control relay output and control circuits. When the fault occurs the relay is deactivated. The first image included is the diagram of the circuit. The second image is a glitch that was showing up occass while idling in the bay. The third image is the relay being shut down by the PCM while driving. The fourth image is the relay being deactivated with a key off condition.

I’m certain that the PCM is shutting down the relay, but I’m uncertain as to why. Additionally if the battery supplies voltage to the control side through the the relay and I’m tapped in after the relay shouldn’t the pattern be different (rising when turned off and falling when commanded on)?

Thanks for any help trying to wrangle this troublesome beast!

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Jeffrey Mobile Technician
Illinois
Jeffrey
 

Are your scope grounds on battery positive? According to the diagram there is constant power to both sides of relay. When TCM grounds relay we should see ground at control side and positive at output side of relay. If you have your green trace at relay control and the ground of green trace on batt negative or alternator case we can see if there is excessive voltage drop on the control side much…

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Manuel Diagnostician
New Jersey
Manuel
 

Pcm tests solenoids at key on if it doesn’t like what it sees limp mode is achieved by turning valve body relay off

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Kyle Diagnostician
Pennsylvania
Kyle
 

Hey Manuel, The fault doesn’t occur until either driving or very rarely during a extended idle in bay. Thanks, ~The Texadelphian~

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Manuel Diagnostician
New Jersey
Manuel
   

Yes this is exactly what I describe maybe not always eloquently but always rushing from job to job. I have had this exact scenario many times in 62te. Fault and limp mode are different check in scan data if limp = true then on following cycle or extended driving will throw codes for solenoid failure or what have you and power input relay .

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Jeffrey Mobile Technician
Illinois
Jeffrey
 

You might also be on the wrong pin of your TIPM. It appears that your diagram is correct. C1 pin 7 of PCM is your control. Pin 43 and 23 of C1 is ignition mode inputs to PCM. I would monitor those also. Now you mentioned solenoid codes! Does the relay code set first or does the solenoid codes set first. I would monitor the trans relay out put for drops in voltage too. According to factory…

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Manuel Diagnostician
New Jersey
Manuel
 

Many times pcm will kill power to relay before solenoid codes set. It is checking them immediately need to drive it load test power ground too. I have had pcm make this failure too but rarer on new style pcm

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Jeffrey Mobile Technician
Illinois
Jeffrey
 

Correct but if the PCM is commanding the relay off there shouldn’t be a relay control circuit code. Are we having a normal shut down of relay and PCM set relay code because someone tried swapping the relay with engine running? Are we having a abnormal shut down of relay to where there are small glitches in relay status that affects the solenoid performance but was not long enough to set a relay…

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Manuel Diagnostician
New Jersey
Manuel
   

It makes the code when goes into limp mode on 2nd ignition so driver is aware more or less friend

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Jeffrey Mobile Technician
Illinois
Jeffrey
 

I have yet to experience that but I’ll believe you.

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Kyle Diagnostician
Pennsylvania
Kyle
 

Hey Jeffrey, the ground for the leads is connected directly to battery negative. The yellow trace is connected at pin 10 at the trans with a wire piercing lead adapter. The green trace is connected at pin 10 in connector C1 at the TIPM with a wire piercing lead adapter. Thanks, ~The Texadelphian~

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Jeffrey Mobile Technician
Illinois
Jeffrey
 

I don’t like your battery positive for relay control when the PCM should be grounding. Piercing at PCM for relay control with a additional channel might help us understand. Searching other year models might find the actual wire diagram.

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Jared Diagnostician
Maryland
Jared
 

PCM sends a 12v signal to TIPM for relay activation on this model

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Gary Technician
Georgia
Gary
 

For what its worth the big ground on side of transmission case . on drivers side normally 13 mm remove and clean ground make sure it's tight . I've had it create all kinds issues.

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Kyle Diagnostician
Pennsylvania
Kyle
 

Thanks Gary, I’ve run into that before. It’s one of the first things I check. Thanks, ~The Texadelphian~

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Jared Diagnostician
Maryland
Jared
 

PCM command dropped off before relay power dropped out. Test power and ground for PCM. If ok, replace PCM. Yes, I have seen this condition at few times.

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Kyle Diagnostician
Pennsylvania
Kyle
 

Hey Jared, Tested power and ground at PCM, all good. Do you think the PCM is just “deciding “ to shut it down? Thanks, ~The Texadelphian~

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Jared Diagnostician
Maryland
Jared
 

Not too sure. Not a circuit board level tech, although I have taken some training on that. If you have no solenoid DTCs, you are monitoring your relay output at the PCM and your relay control at TIPM, and you get the results you have (PCM dropout before Relay dropout), it's a bad brain. Wether it's a poor solder joint, or a bad driver circuit with this issue, I can't say. All I can say is that I…

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Kevin Technician
Tennessee
Kevin
 

I’m going to agree with Jeffrey Hendrix here. That scope image is making me scratch my head and not sure if you have the right placement. 2nd, per code criteria the code sets when monitoring output voltage AT the PCM not the trans so I would monitor the the yellow/orange wires there too compared to relay output voltage(maybe suspecting faulty splice??). 3rd, what are your other solenoid codes?

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Kyle Diagnostician
Pennsylvania
Kyle
 

Hey Kevin, That’s a fair point about checking the feeds from the relay to the PCM. As to the solenoid codes it varied, I suspect this was due to the system losing the supply voltage when checking a specific solenoid during driving. Thanks, ~The Texadelphian~

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Caleb Diagnostician
Indiana
Caleb
 

Agree with Jeff on this. How can Circuit T16 have power if the PCM is not grounding T15? Something does not add up. Manuel you are correct about limp mode. However I have never seen limp mode set this fault. This fault means the trans control relay circuit is broke, hence the fault code. Just my opinion anyway.

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