kozman16
Junior Member
Hey guys,
I am new on this forum, but I used it recently trying to diagnose my 2013 Ram 1500. I figured out the issue and I wanted to share my experience in hopes that it will help others.
Backstory:
We had a really wet/heavy snow and freezing temps the following night. The bottom half of the truck was packed with ice. The first thing that happened was a “service shifter” message. After that all hell broke loose with intermittent random messages and all dash lights blinking on and off. After parking the truck and turning it off, it acted like the battery was dead. The gauges would flicker but after 30 seconds the truck would come alive, flashing all the messages again. During this I could randomly start the truck/put it in gear. I thawed the truck out inside for 2 days, no change. I checked battery voltage and it was at 12.3v. Replaced the battery with no change.
After reading multiple forums, I started troubleshooting the “no bus” message. Hooked up the scanner and got 16 codes all related to loss of communication between modules. Checked for continuity between CAN+ and CAN- at the OBDII connector and got around 60 ohms, which is good. But when I checked from CAN- to ground I got ~190 ohms and from CAN+ to ground I got ~280 ohms. (Not sure what the correct values it should be.)
With the key on, I located the CAN (C) star connector under the dash on the drivers side and started disconnecting each module one by one until the dash started to act normal. Finally disconnecting the yellow/dark green wire connector stopped all the issues.
Looking into the wiring diagrams, turns out it’s the TMPS module. Checked continuity and found 90 ohms to ground on the (yellow) CAN- wire and OL on the (green) CAN+ wire. Disconnected the TPMS module and the wiring checked good between both connectors. I opened up the TPMS module and found the board shorted between the power/ground terminals due to corrosion. Most likely due to the ice/water intrusion.
I have aftermarket rims without tire pressure sensors installed so removing the module completely doesn’t bother me at all (except for having the tire pressure light on the dash). Funny enough, it never popped the fuse for the TPMS.
I am a licensed A&P Avionics technician, not certified in automotive. But performing simple continuity/voltage checks and reading the wire diagrams will help you diagnose your problems. I really hope this helps someone and saves a bunch of headaches/money.
I am new on this forum, but I used it recently trying to diagnose my 2013 Ram 1500. I figured out the issue and I wanted to share my experience in hopes that it will help others.
Backstory:
We had a really wet/heavy snow and freezing temps the following night. The bottom half of the truck was packed with ice. The first thing that happened was a “service shifter” message. After that all hell broke loose with intermittent random messages and all dash lights blinking on and off. After parking the truck and turning it off, it acted like the battery was dead. The gauges would flicker but after 30 seconds the truck would come alive, flashing all the messages again. During this I could randomly start the truck/put it in gear. I thawed the truck out inside for 2 days, no change. I checked battery voltage and it was at 12.3v. Replaced the battery with no change.
After reading multiple forums, I started troubleshooting the “no bus” message. Hooked up the scanner and got 16 codes all related to loss of communication between modules. Checked for continuity between CAN+ and CAN- at the OBDII connector and got around 60 ohms, which is good. But when I checked from CAN- to ground I got ~190 ohms and from CAN+ to ground I got ~280 ohms. (Not sure what the correct values it should be.)
With the key on, I located the CAN (C) star connector under the dash on the drivers side and started disconnecting each module one by one until the dash started to act normal. Finally disconnecting the yellow/dark green wire connector stopped all the issues.
Looking into the wiring diagrams, turns out it’s the TMPS module. Checked continuity and found 90 ohms to ground on the (yellow) CAN- wire and OL on the (green) CAN+ wire. Disconnected the TPMS module and the wiring checked good between both connectors. I opened up the TPMS module and found the board shorted between the power/ground terminals due to corrosion. Most likely due to the ice/water intrusion.
I have aftermarket rims without tire pressure sensors installed so removing the module completely doesn’t bother me at all (except for having the tire pressure light on the dash). Funny enough, it never popped the fuse for the TPMS.
I am a licensed A&P Avionics technician, not certified in automotive. But performing simple continuity/voltage checks and reading the wire diagrams will help you diagnose your problems. I really hope this helps someone and saves a bunch of headaches/money.
