2016 Ram 3500 - No Crank

Craig Mobile Technician Georgia Posted   Latest   Edited   Bounty  
Resolved
Driveability
Electrical
2016 Ram 3500 Laramie 6.7L (L ETK 320hp) 6-spd (68RFE) — 3C63R3ML2GG170222
No Crank

Hi Everyone. We are assisting another shop with a 2016 Ram 3500 6.7L A/T 4WD (3C63R3ML2GG170222). Customer complaint is a No Crank Condition. Claims this all started at once, after stopping at a store. Mentioned that the vehicle would not Crank, and then the Alarm started sounding briefly. Claims there were no prior issues. This vehicle is equipped with Push Button Start. This is a stock truck, and has not been “tuned”. When depressing the Brake and the Push Button, the Instrument Cluster, Radio, ect, all turn on. The other shop found that if the Ignition is switched On and the Starter Relay jumped, the truck will start and run with no issues. It does not appear, according to scan data, that this is an Immobilizer (SKIM) issue. A full system scan only revealed this Rear Camera DTC (see image). It was also verified that the No Crank Condition is also present when attempting to remote start this vehicle. 

While monitoring the PCM, RFH, and BCM, it appears all Modules are seeing that Crank is being requested (see image). The shop has already replaced the BCM and the KIN (due to TSB # 08-028-18), but the problem still remains. The BCM supplies the Starter Relay Coil Circuit with voltage when commanding the Relay on, and the PCM should provide ground on the other side of this Coil Circuit. It has been verified the PCM is supplying ground, but the BCM is not providing voltage. While monitoring scan data, it was found that the BCM is NOT commanding the Starter Relay on (see image). According to Service Information, the BCM must both see voltage supplied on the F20 Circuit (Ignition Run/Start Output Control Circuit) by the RFH and Bused Messages from the RFH about the Crank request, before the BCM will activate the Starter Relay. Voltage was verified on the F20 Circuit when turning the Ignition On and attempting to Crank. It was also verified that the Gated Park Switch is changing states in scan data, when the Shifter is moved in and out of Park.

Using Bi Directional Controls in the BCM, the Starter Relay can be commanded on (see image). The Starter does crank, but appears that the BCM is toggling it no matter if “Toggle” or “On” is selected in.

I am trying to gather more data before going back out on this vehicle, as to what would cause the BCM, in this case, to not actuate the Starter Relay. 

I appreciate your time.

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William Technician
West Virginia
William Resolution
 

Have you checked the TRS park signal for wire integrity from end to end? I have seen Chrysler do this on other vehicles, where the power to the starter relay is withheld because of an analog input and none of this information will show up on the scan tool. Had a 14 jeep that would no start do to a broken wire on the trs. Everything read right on the scan tool but would not start with the key…

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Craig Mobile Technician
Georgia
Craig Default
 

Hi William. Thanks for the response. I have not verified this Circuit by manually testing it yet, but only using scan data to monitor the Gated Park Switch PID. I will scope this Circuit and monitor activity. Thanks!

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William Technician
West Virginia
William Default
   

Hope this helps as well. The BCM requires two signals from the RF HUB to verify the ignition is in the run or start position. The voltage on the F20 circuit is one of these signals. It can be monitored in both the RF HUB and BCM data display screens as the Ignition Run/Start under the “Sensor” value. The run or start position voltage on this circuit should be at or close to Battery…

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Craig Mobile Technician
Georgia
Craig Default
 

Hi William. See my update below. Thanks!

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William Technician
West Virginia
William Default
 

Anytime! Glad I could help.

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Michael Technician
New Jersey
Michael Default
   

Hey Craig, You dont need to create a flight recording to get all the PIDs you need on the same screen. When you're in a module highlight a PID then at the top click "Add to vehicle data". This sounds like a Hub to me. I would verify G20 & comm on D122. Also A910 & Z906 while attempting to crank. Last I would unplug C12 at IP STAR connector and watch comm while attempting to crank. Hope…

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Craig Mobile Technician
Georgia
Craig Default
 

Hi Michael. I will test these Circuits when I get back to the vehicle. Thanks

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Tanner Instructor
South Carolina
Tanner Default
 

One thing that I am wondering about is the BCM that was replaced. Any idea if the BCM was new or used and also if the part number has been checked? I went through the charts I could find and it appears to me your inputs are all correct. I feel like maybe the bcm is looking for an input that might not be there maybe because of a configuration or incorrect bcm. If there are no other data pids in…

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Craig Mobile Technician
Georgia
Craig Default
 

Hi Tanner. It was a new OE BCM. I did verify the part numbers. I did the BCM Replaced Option in the RFH. I have checked and do not see any other Configurations I could select for this vehicle. This vehicle had the same exact symptoms and scan data with the original BCM.

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George Diagnostician
British Columbia
George Default
 

Hi Craig sounds like BCM is in a confused state I would erase all codes and or do I complete reset by discharging capacitors then recheck inputs to see if any thing is missing

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Craig Mobile Technician
Georgia
Craig Update
   

Thank you to everyone that helped with this. We were finally able to get this figured out. Turns out the Transmission Range Sensor had an internal fault on the TRS T41 Circuit Circuit. This TRS T41 Signal Circuit from the PCM is suppose to be pulled low (0V) by the Transmission Range Sensor when the Transmission is either in Park or Neutral. We found that this Circuit remained at 12V, even when…

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Caleb Diagnostician
Indiana
Caleb Default
 

Nice work Craig!! FCA has a great scan tool but everything else is so generic. That would have stumped me also.

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