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Go to start car and get no fob detected, so grab my other fob. Attempt again, car cranks and warning lights and lots of alerts DIC traction, low fuel, etc and car finally starts. Begin to drive and car running poorly and eventually clears up. CEL had come on and I get to my destination. Leave my destination and car starts right up and CEL still on. Scan car when I get home with hp tuners and get DTC U0100 (lost comm with ecm) and U2105 (can bus error) so I clear codes. Next day start the car and drive it zero issues. Go to start car later that night and will not start, push and acts like dead battery. Proceed to keep trying to push to start and gauges delay coming on each time, car cranks but won't start, car eventually starts and runs poor. Get it home and it runs fine and this time no codes. Next day I replace battery and made sure its good. Attempt to start car and its dead, push start button and long delay, gauges come on and all lights act erratic and all the warnings in the DIC. Currently the car sits dead you can turn to run with long delay prob 15sec, gauges sweep and every warning messages comes on, check engine lights pulses and lots of relay chatter. HP tuners and handheld will power up but won't communicate. Did a lot of troubleshooting and traced to ECM. Unplugged ECM and now you can turn car on and electrical system is stable. Still a long delay for gauges to turn on but no relay chatter and dash isn't going crazy. Is it a bad ecm?
Things I've done:
New starter, crank relays, checked all fuses BCM and Under hood, inspected wires to all
Cleaned all grounds chassis and connections to BCM ECM connections
New Start button
Checked for voltage at fuses and fuse box
Tried a new/used BCM same thing happens
OHM out OBD2 port 60 ohms and 120 with ecm unplugged, CAN bus 2.2 and 2.1 v and constant 12v
12v at ECM harness pin 19 and 20.
What am I missing? ECM just die that quick? is that what's causing the whole system to crash?
Yes the ECM is causing your problems and is bringing down the high speed bus…you need to check the ECM powers and GROUNDS…if they are good the ECM is bad…the CAN transceiver is located in the ECM and if its bad you’ll have to replace the module….the 2 each 120 ohm resistors are in the BCM and ECM…if you disconnect the ECM you will see 120 ohms between pins 6 and 14…you don’t check the ECM powers with a DVOM…you must “load” the circuit…I use a 3 amp test bulb connected to ground and if those 2 powers are good the light will be bright…voltage drop testing is the BEST way to test but don’t think you are familiar with that testing method…moving this to Tech.
You have a IGNITION feed on 47 from Powertrain Ignition 1 relay and through fuse 9…ignition must be on to check it…ground is G106…you hook the test light to B+ to check the ground…G106 is colocated with the negative battery cable above the starter.
Yes the ECM is causing your problems and is bringing down the high speed bus…you need to check the ECM powers and GROUNDS…if they are good the ECM is bad…the CAN transceiver is located in the ECM and if its bad you’ll have to replace the module….the 2 each 120 ohm resistors are in the BCM and ECM…if you disconnect the ECM you will see 120 ohms between pins 6 and 14…you don’t check the ECM powers with a DVOM…you must “load” the circuit…I use a 3 amp test bulb connected to ground and if those 2 powers are good the light will be bright…voltage drop testing is the BEST way to test but don’t think you are familiar with that testing method…moving this to Tech.
What are the correct pins to test? I have black and gray J1 and J2. 19,20 on J1 had the 12.2 but haven’t been able to find what pins chassis ground is.
“Chassis Ground” is terminal 4 on the DLC…it is ground G201 which is at the bottom of the A pillar…no need to check that because it is not an ECM ground…just 1 ECM ground which I pointed out.
“Chassis Ground” is terminal 4 on the DLC…it is ground G201 which is at the bottom of the A pillar…no need to check that because it is not an ECM ground…just 1 ECM ground which I pointed out.
so from pin 47 to the ground above the starter on the block?
I don’t know what you mean and what you are trying to do ??…47 is an ignition feed and G106 is the ECM ground…like I said I don’t know how you check your power feeds but I use a 2 or 3 amp headlight bulb….I use the same bulb to check the ground which is 73.
I don’t know what you mean and what you are trying to do ??…47 is an ignition feed and G106 is the ECM ground…like I said I don’t know how you check your power feeds but I use a 2 or 3 amp headlight bulb….I use the same bulb to check the ground which is 73.
Im looking to check power and grounds to the ECM. If I have good ground and power that eliminates power and ground issues and points to a bad ecm. So looking for PIN numbers to check for continuity to ground and PIN numbers to verify constant and ignition 12v
The ECM terminals for power and ground are in post 3…are you familiar with reading them ??…at the bottom where the ECM is the power terminals are the numbers… 20, 47, 19, and the ground is 73…these are ALL on the X1 connector…and as I mentioned continuity is NOT how a ground is checked…do you know the purpose of a ground ??…if not it carries back the current of circuit and in this case it carries the current from the ECM back to battery negative…any resistance will cause all that current not to be used up…if that ECM wire has 100 copper strands and 75 of them are broken you will still have good continuity with an ohm meter but will those 25 good strands be able to carry the current…PROBABLY NOT…you get what I’m saying ??…did you watch that video ??…B+ is battery feed and is powered all the time…ignition feed is powered when the Ignition is on…if all powers and grounds are good it may be a bad ECM…I’m not there looking over your shoulder so I can’t know if you are doing it correctly.
09 Z06 No start, electrical issues
