40 way L-body bulkhead connector

[black86glhs]

I made a small pdf file showing the terminals and wires in the L-body underhood bulkhead connector. It shows some upgrades in wire size for many of the terminals.

[minigts]

So what was the reasoning with changing gauges? Just curious. I'm sure it won't be an issue, but I always try and stay with the same gauge when mending or replacing wires.

[black86glhs]

So what was the reasoning with changing gauges? Just curious. I'm sure it won't be an issue, but I always try and stay with the same gauge when mending or replacing wires.

The power supply ones were increased in size because I believe the factory size is just barely enough. Some of the others is due to 18ga being a readily available size and in the correct color. Plus, some of the wires, like the temp sending unit on the block are easy to break due to how thin they are. I would prefer them to be a thicker wire. I'm not worried about the small weight increase that I'll end up with.

[minigts]

Hehe. I was thinking more of the gauge thickness with regards to current, not the weight. I'm sure it will be fine though, don't see why not.

[Reeves]

The heavier gauge has the capability to handle MORE current. Only downside is the added weight and bulk.

Thanks for the PDF!

[rx2mazda]

Could have used that PDF like a month and a half ago!

[minigts]

The heavier gauge has the capability to handle MORE current. Only downside is the added weight and bulk.

Thanks for the PDF!

Man, the one and ONLY time I ever went from one gauge to another, I fried the starter relay. That's the main reason why I had always stayed with the same gauge. Granted, I know I grounded something that shouldn't have been grounded... I was always worried I do something else or damage something else. Kinda like choking on a peppermint when I was a kid, so I didn't ever eat another one until I was like out of high school!

[shelbydave]

Man, the one and ONLY time I ever went from one gauge to another, I fried the starter relay. That's the main reason why I had always stayed with the same gauge. Granted, I know I grounded something that shouldn't have been grounded... I was always worried I do something else or damage something else. Kinda like choking on a peppermint when I was a kid, so I didn't ever eat another one until I was like out of high school!

In that case you would want to go with a smaller gauge so that you can sacrifice the wiring harness instead of the easily changeable starter relay.

You can also go with smaller gauge wiring to protect those 25 cent fuses too...

[black86glhs]

Hehe. I was thinking more of the gauge thickness with regards to current, not the weight. I'm sure it will be fine though, don't see why not.

I want the added current capacity, if needed later on. The interior part of the harness is still factory. The only reason I mentioned the weight, is that it is one of the first things brought up when you say your using the larger wire. I don't care. It is a small amount that I can make up some where else, if needed.

[minigts]

In that case you would want to go with a smaller gauge so that you can sacrifice the wiring harness instead of the easily changeable starter relay.

You can also go with smaller gauge wiring to protect those 25 cent fuses too...

Man the fear that hit me is something I don't ever want to go through again. Scared the pee out of me when it did it because there was a slight delay.

I want the added current capacity, if needed later on. The interior part of the harness is still factory. The only reason I mentioned the weight, is that it is one of the first things brought up when you say your using the larger wire. I don't care. It is a small amount that I can make up some where else, if needed.

Yeah the weight thing always makes me laugh. I can understand re-wiring something and adding components but going from 18 to 14 isn't going to add a significant amount of weight that someone will see in the 1/4 mile. And if you do, remember to go to the bathroom before a 1/4 mile pass.

[black86glhs]

Man the fear that hit me is something I don't ever want to go through again. Scared the pee out of me when it did it because there was a slight delay.




Yeah the weight thing always makes me laugh. I can understand re-wiring something and adding components but going from 18 to 14 isn't going to add a significant amount of weight that someone will see in the 1/4 mile. And if you do, remember to go to the bathroom before a 1/4 mile pass.

Yeah...take off your coat before going down the track...LOL.

[black86glhs]

Could have used that PDF like a month and a half ago!

If you would have done my HW I would have done it for you no problem Carroll!!!

[rx2mazda]

If you would have done my HW I would have done it for you no problem Carroll!!!

HW?

[black86glhs]

HW?

homework....physics to be precise.

[rbryant]

As a side note many of the wire size increases that you did were also done by the factory when they went to the 50 pin bulkhead.

I didn't realize this until I started making my megasquirt harness. I am changing the bulkhead to 50 pin so that I can use the empty slots for wiring through the bulkhead back to megasquirt in the cabin. Those signals were formerly connected on the passenger side LM.

When I converted to SMEC I already plugged the passenger side hole and I like them to all go through the same bulkhead so 50 pin was the way to go.

If you are running a SMEC then 40 pin is just fine and the wiring sizes are good upgrades if you add extra interior electronics, lights, etc.

Adding dedicated headlight relay(s) also makes it so it really isn't as necessary to increase the wire sizes of the headlight feed wire and headlight outputs on the bulkhead. This is because the real power draw is through the relay(s) rather than through the headlight switch and bulkhead.

Sometimes the overkill is a good thing though and it is easy so why not.

-Rich

[minigts]

As a side note many of the wire size increases that you did were also done by the factory when they went to the 50 pin bulkhead.

I didn't realize this until I started making my megasquirt harness. I am changing the bulkhead to 50 pin so that I can use the empty slots for wiring through the bulkhead back to megasquirt in the cabin. Those signals were formerly connected on the passenger side LM.

When I converted to SMEC I already plugged the passenger side hole and I like them to all go through the same bulkhead so 50 pin was the way to go.

If you are running a SMEC then 40 pin is just fine and the wiring sizes are good upgrades if you add extra interior electronics, lights, etc.

Adding dedicated headlight relay(s) also makes it so it really isn't as necessary to increase the wire sizes of the headlight feed wire and headlight outputs on the bulkhead. This is because the real power draw is through the relay(s) rather than through the headlight switch and bulkhead.

Sometimes the overkill is a good thing though and it is easy so why not.

-Rich

Luckily with the 40 way, only about 25 pins are used (well with my conversion anyways), which leaves about 15 free for whatever else. The extra 10 with a 50 pin will probably be useful one day though.

[black86glhs]

As a side note many of the wire size increases that you did were also done by the factory when they went to the 50 pin bulkhead.

I didn't realize this until I started making my megasquirt harness. I am changing the bulkhead to 50 pin so that I can use the empty slots for wiring through the bulkhead back to megasquirt in the cabin. Those signals were formerly connected on the passenger side LM.

When I converted to SMEC I already plugged the passenger side hole and I like them to all go through the same bulkhead so 50 pin was the way to go.

If you are running a SMEC then 40 pin is just fine and the wiring sizes are good upgrades if you add extra interior electronics, lights, etc.

Adding dedicated headlight relay(s) also makes it so it really isn't as necessary to increase the wire sizes of the headlight feed wire and headlight outputs on the bulkhead. This is because the real power draw is through the relay(s) rather than through the headlight switch and bulkhead.

Sometimes the overkill is a good thing though and it is easy so why not.

-Rich

I fully agree Rich. I was thinking about the wiring for the headlights. I think I'll do it just in case I don't get the relays done before getting it running. I know me...lol.

[t3rse]

Man, the one and ONLY time I ever went from one gauge to another, I fried the starter relay. That's the main reason why I had always stayed with the same gauge. Granted, I know I grounded something that shouldn't have been grounded... I was always worried I do something else or damage something else. Kinda like choking on a peppermint when I was a kid, so I didn't ever eat another one until I was like out of high school!

I changed everything to 12 ga and removed everything non-critical (3#...no ----) and haven't fried anything.

[black86glhs]

I changed everything to 12 ga and removed everything non-critical and haven't fried anything.

Jon's not good with wiring...LMAO!!!

[rbryant]

Luckily with the 40 way, only about 25 pins are used (well with my conversion anyways), which leaves about 15 free for whatever else. The extra 10 with a 50 pin will probably be useful one day though.

There are only about 5 spares by the time I wire up everything I want from megasquirt.

I am also controlling purge solenoid, fan control, boost control, O2 sensor, electrical power steering high/low, charge temp, coolant temp, 3 external electrical gauges, electric speedo, fuel injectors, crank sensor, 2 coil outputs for wasted spark, etc. And that doesn't include cruise control.

This is a special case but I defiantely needed 50 pins.

-Rich