How to check your ECM ground

Reply Subscribe

Thread Tools

Search this Thread

02-23-2013, 03:52 AM

steveinfrance

Veteran Member

Thread Starter

Join Date: Dec 2011

Location: Limousin, France

Posts: 6,278

Likes: 277

Received 687 Likes on 590 Posts

How to check your ECM ground

Apart from a bad battery one thing to suspect when odd codes get thrown is a bad ground somewhere.
It might help to know that the OBD port pin 5 goes to ground via the ECM while pin 4 is grounded directly.
Pin 16 is battery volts so you should see the same voltage between 4 + 16 as 5 +16, and the resistance between 4 +5 should be a fraction of an ohm.

Attached Images

Last edited by steveinfrance; 02-23-2013 at 06:18 AM.

Reply Like

The following 13 users liked this post by steveinfrance:

berlin1977 (02-23-2013), BobF (02-23-2013), britannia (02-24-2013), GordoCatCar (02-24-2013), heima (02-25-2013), and 8 others liked this post.

02-24-2013, 10:00 AM

steveinfrance

Veteran Member

Thread Starter

Join Date: Dec 2011

Location: Limousin, France

Posts: 6,278

Likes: 277

Received 687 Likes on 590 Posts

Pins 4- 16 is also an easy way to measure battery voltage without pulling the boot liners apart.
Bear in mind your OBD reader gets its power from pin 12 so leaving it connected will flatten your battery.

Last edited by steveinfrance; 05-23-2013 at 03:40 AM.

Reply Like

The following 2 users liked this post by steveinfrance:

clyons (02-24-2013), MRomanik (02-24-2013)