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Hey guys and gals, just finished a build requiring an engine removal and replacement using Fyreants how to. I went to get my stock tune off the car and heard a buzzing. Thought it was fuel pump at first and discovered it was actually the ECM relay at position #62 on my 2016 main fuse block. Tried to start it, same buzzing with no starter engagement.
Voltage is good at over 12.5. Disconnected the 2 power cables at the fuse block, removed and checked for damaged or misaligned pins, and then reinstalled. Same problem. HPTuners of course can’t read the stock tune.
The dash fires up. Lights and door locks work. Radio works. OnStar even sent me an email when I powered it all up.
I swear these cars have more redundant grounds than a 737 Max 8!
Left ground off at drivers lower front of block! Damnit!
Back to work on this thing......
I know this an old thread but im having a similar issue, I also pulled my engine and reinstalled. I have all grounds that I can find connected. HP tuners won't read my tune either, any ideas?
I know this an old thread but im having a similar issue, I also pulled my engine and reinstalled. I have all grounds that I can find connected. HP tuners won't read my tune either, any ideas?
have the same problem on a car here right now trying to diagnose. May change the fuse and see what happens
New fuse and new battery didn’t fix the problem.. been busy so that’s all I had a chance to do! Going to get it on my lift and see if a ground worked it’s way loose..
I have a video, if I can figure out how to post it, just a dim check engine light blinking fast and can hear the ECM fuse buzzing
Still battling this, had GM install a new BCM, checked all the grounds, still no luck…
removed ECM to program new ECM, was unsuccessful, so installed old ECM and fuse clicking went away and started right up.. ran for 1.5 min and cut off.. restarted and ran for about 45 seconds and cut off..
tried the next day and ECM fuse buzzing again and will start every 5-10 attempts and run for about 30 seconds
were any of you able to figure out the issue, removed motor for a cam and after install it ran for a good week and after that it started doing the ecu buzzing and not starting.
were any of you able to figure out the issue, removed motor for a cam and after install it ran for a good week and after that it started doing the ecu buzzing and not starting.
Do you mean a relay is buzzing and not the ECM ??…which relay ??…it helps to know the model year as a minimum…buzzing relay is usually low voltage on the coil side of the relay but can also be on the ground side.
Is it Relay 62 (ECM Relay) ??…that should be the KR75 Relay below….you can try swapping or replacing the relay first….do you know how to do a voltage drop across terminals 86 and 85 ??…I use a relay tester and with a DVOM check across 86 and 85 with the DVOM…if you have thin copper wire you could wrap it around the relay blades for both and then reinsert the relay and while attempting to start the car you would read the voltage drop…if this testing is over your head seek out an auto electric shop.
yes it is that relay. we've done all the relay test already, even replaced the relay, it is good also the check engine light rapidly flashes as the ecu relay is buzzing. after about 5 min it stops and the car is able to start but it only stays on for about 30 sec
Oh, if the MIL is flashing rapidly I would check the powers and grounds on the ECM…if you have a scan tool or even a code reader see if you can communicate with the ECM…to check powers and grounds I normally use a bulb that draws a few amps or do a voltage drop check with a DVOM.…looks like 5 Ignition feeds and one battery feed…there are 2 grounds which splice into G100 as in the wiring diagram I posted…the best way is a voltage drop as in the video below…you can see the MIL light circuit on the far right…the ECM supplies the ground…if low ignition voltage to the MIL from the ECM it may flash…I would check those 5 fuses 4,15,27,28) that are fed from the relay…they feed the ECM…ignition must be on to energize the relay.
Oh, if the MIL is flashing rapidly I would check the powers and grounds on the ECM…if you have a scan tool or even a code reader see if you can communicate with the ECM…to check powers and grounds I normally use a bulb that draws a few amps or do a voltage drop check with a DVOM.…looks like 5 Ignition feeds and one battery feed…there are 2 grounds which splice into G100 as in the wiring diagram I posted…the best way is a voltage drop as in the video below…you can see the MIL light circuit on the far right…the ECM supplies the ground…if low ignition voltage to the MIL from the ECM it may flash…I would check those 5 fuses 4,15,27,28) that are fed from the relay…they feed the ECM…ignition must be on to energize the relay.
were any of you able to figure out the issue, removed motor for a cam and after install it ran for a good week and after that it started doing the ecu buzzing and not starting.
I might have missed that the engine was REMOVED…if you have a 12 volt test light connect it to battery negative and probe the engine block while attempting to start the car…if light illuminates the engine block ground is bad and may be loose…if you have jumper cables connect to battery ground and the engine block and see if the car starts.
ECM relay buzzing - engine won’t start
