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2006 cadillac dts intermittent no com with few diff modules creating no start
I have a 2006 cadillac DTS. The car has has various u codes. at times i can not comunicate with tcm,bcm,ecm,abs. i have checked the ohm on the dlc connector when i have no com and i read 63-64 ohms all modules connected.I have also checked the power and grounds to the modules with a test light did not go as far as to take voltage readings. whenever i disconnect any module the resistance jumps to 123ohms. which i think is supposed to be normal? if i pull up data from module with intermittent fault data will display and then shortly thereafter not comunicate. Any help would be greatly appreciated. any other test i could do would greatly be appreciated.
c0550 - ebcm detects an internal malfunction
c0899 - device voltage low - ignition voltage to ebcm is less than 9v for 100 msec.
b1325 - device power circuit - system voltage below or above the calibrated value of 9v -18v
Clear the codes, make sure battery is good and terminals tight. Check battery for excessive ac ripple. Check what your low speed serial data looks like (dlc pin 1). 60 ohms on high speed gmlan and your image attachment shows it's intact, not shorted to each other, not shorted to power nor ground. Scope capture looks a little wavy haha. c0550 points to bad ebcm, if that code keeps coming back unplug that module and jump the terminals so the 120 ohm resistor in the ECM stays connected on the network.
hey there car is still beating me up. i have a capture on my pin 1 of dlc the low speed can network. which shows constant communication. hours after car has been off. i also noticed that the data from my radio on the scan tool does not match power mode of the bcm. the radio data will show power mode off with car running and radio is playing. i cycled the key and it sometimes changes to acc or to run, im thinking now its an ignition problem or the bcm is not sending signal sometimes to radio. i need to look over how that circuit operates. now with the pin 1 capture shouldnt the waveform be all squarewaves for communication like on the high speed can lines?
Missing termination resistor(inside the module).
you’ll see how the voltage is going too high for the can network specs?
As far as the location of the terminating resistor SI shows that on is internal to the PCM and the other is in the rear fuse box.
Making Pressure Differential Sensors (PDA Sensors) for pressure pulse diagnostics.
Currently servicing Central Texas.
Last edit: 3 years 10 months ago by John Curtis. Reason: Correcting myself with service information
thank you. im not sure if it is a flood vehicle. i am going to monitor the signal and start attemting to unplug modules. was hoping i did not have to take dash apart to get to the instrument panel cluster but that appears to be where i may have to go.
First what is the list of modules you can communicate with when no problem occurs? Compare that to the list when malfunction occurs. See if it’s the pins 6 and 14 that’s messed up or the single wire communication. I’m betting it’s the ebcm since it has an internal fault code. Unplug it jump the cam lines with jumper wires to bypassed the module.
I am having this same problem with a 2007 DTS.. was running fine .. then stopped running.. when I unhooked the battery and hooked it back up.. I am unable to get the car to start...
It's showing loss of communication with ecm bcm and a few other modules..
I am lost as go what the problem is.. I believe it's wiring that's shorted out or has gone bad somewhere...