ctuinstra
Goblin Guru
I've seen a lot of post recently with those have have had trouble starting the engine for the first time. Many of them tend to be the same issues of some form or another over and over. So I thought I would start a thread about what to do if the engine doesn't start the first time and common things you can check for. I'm not the expert on this and I'm looking for others to correct me and add to the subject. If there is a correction, I will correct this original post.
A couple of key things to remember that are very important:
This is by far the most common issue with the engine not wanting to do anything. Without a GOOD ground on every circuit, current cannot flow properly. One poor ground on one circuit can cause current to feed back through other circuits and use their grounds and all kinds of weird things can happen. Electricity will NOT flow through paint or powder coating. If you did not clean off all the paint or powder coat on your ground lugs and bolts, STOP now and go back to clean them up. Even if the metal is clear of paint or powder coating, I still suggest using a wire wheel on a die grinder or something to scratch the the heck out of the surface of the metal to make the best possible contact.
This is an actual ground I found on my donor. This is NOT a good ground.
This is what your ground lugs should look like:
I would also recommend you clean off the underside of the engine mounts so as to get a good ground through them. If not, at least connect the large ground cable from the engine block to the rear frame ground terminal.
Connect this cable to this terminal (mine is not yet cleaned off completely yet).
Another very important ground is the ground on the headlight harness. There is a large white block connector on the underside of the fuse box, this is the connection for the headlight circuits. Believe it or not, there is a very important ground in there used for the relays in the fuse box. Without it, the relays will not activate.
The BCM also has to have a good ground. Make sure to clean all the contact points and use star washers if you have them.
A couple of key things to remember that are very important:
- Grounds are very important and one of the most common issues (more information soon).
- The High Speed GM LAN serial bus must be connected between the BCM (Body Control Module) and the ECM (Engine Control Module).
- Clutch and Brake switches have to be activated properly before it will crank.
This is by far the most common issue with the engine not wanting to do anything. Without a GOOD ground on every circuit, current cannot flow properly. One poor ground on one circuit can cause current to feed back through other circuits and use their grounds and all kinds of weird things can happen. Electricity will NOT flow through paint or powder coating. If you did not clean off all the paint or powder coat on your ground lugs and bolts, STOP now and go back to clean them up. Even if the metal is clear of paint or powder coating, I still suggest using a wire wheel on a die grinder or something to scratch the the heck out of the surface of the metal to make the best possible contact.
This is an actual ground I found on my donor. This is NOT a good ground.
This is what your ground lugs should look like:
I would also recommend you clean off the underside of the engine mounts so as to get a good ground through them. If not, at least connect the large ground cable from the engine block to the rear frame ground terminal.
Connect this cable to this terminal (mine is not yet cleaned off completely yet).
Another very important ground is the ground on the headlight harness. There is a large white block connector on the underside of the fuse box, this is the connection for the headlight circuits. Believe it or not, there is a very important ground in there used for the relays in the fuse box. Without it, the relays will not activate.
The BCM also has to have a good ground. Make sure to clean all the contact points and use star washers if you have them.
