Trans planting a 1987 TBI out of a G20 onto a 1963 Impala

**turbopowered68** · 10-17-2015

As it says
I am in the middle of transplanting a 87 TBI engine into my Dad's 1963 Impala.
i have everything out of the van except the dash harness and firewall plug.
Anyone sell the firewall plug with labeled leads that can facilitate completing the wiring?
Also which is the fuel pump plug?
Thanks for your help guys
David

**1project2many** · 10-17-2015

Most vehicles don't actually use a plug at the firewall. They use a hard plastic pass-through connector. But some of the trucks, mostly square body types, didn't use a hard firewall plug. The harness passed through a rubber grommet instead. I believe some of the early S10 Blazers might have been the same. A harness with that grommet wouldn't need to be labelled and you could use a hole saw to open the firewall instead of trying to cut a square or rectangle hole.

Here are some examples. In the first image it is behind the dipstick tube. In the second image it is the focus of the photo.

Here is a Toyota engine wiring grommet. It's very nice and can be taped into the harness.

**Fast355** · 10-17-2015

Van ECM sits under the drivers seat and the harness comes up through the floor with a rubber grommet. Only a hand full of wires that go into the connector under the hood need to be connected to make the engine run. Even the ALDL port is wired up under the carpet/floor mat.

**turbopowered68** · 10-17-2015

I need something like this but for the tbi set up http://www.casperselectronics.com/st...oducts_id=1181

**1project2many** · 10-17-2015

I don't know who sells that plug for the van with circuits labelled. We use service manuals with circuits shown when we need to diagnose a circuit passing through one. Most of the circuits in that connector are unrelated to efi and can be deleted.

**turbopowered68** · 10-17-2015

Originally Posted by 1project2many

I don't know who sells that plug for the van with circuits labelled. We use service manuals with circuits shown when we need to diagnose a circuit passing through one. Most of the circuits in that connector are unrelated to efi and can be deleted.

Doesn't ALL the power for the engine pass through that plug?
The fuses are all on the other side (cabin) of that bulkhead, Ignition, starter and so on.

ok So is there a wiring schematic specifically for that bulkhead?
If i can't get the dash side part i guess i can just cut the bulkhead and tie in a fuse block then pick out my switched leads from there.

Side note-- i used that dashmatting harness that i linked on one of my projects and it was super simple.
I used and OE engine harness plugged in the dashmatting harness tied in 5 prelabeled leads and i was DONE.

Thanks for the replies and help.

Edit from digging around i found out that the plug and information that i am looking for is called C100.
hope that helps

**mytmouz** · 10-17-2015

No, some of the power comes from the fuse side, I believe. I know in my case from using a truck harness, that the power to the injectors was from over there... I had cut the harness at that block when I got it, I soldered the connections I needed to the transplanted vehicle electrical system...

**lionelhutz** · 10-17-2015

Are you asking about an engine wiring harness to connect behind the fuse block into the original car wiring or are you asking for a harness to pass-through the new fuel injection wiring?

The typical engine harness passes all fuel injection wiring through the firewall with a plug to fill the hole with the computer on the inside of the firewall. This harness has a connector under the dash where power and/or other connections such as speed signal and ALDL port are made to the under dash harness. There is often also a junction block and some battery power connections under the hood on the firewall that powers the harness.

Then, there can also be a bulkhead connector behind the fuse block that is also part of the engine harness but it typically just wires the sensors and other stuff that isn't injection related. The closest to injection related coming through that plug might be the power wire for the ignition system.

I think you're asking for a new bulkhead connector to tie into the original car wiring but I'm just not sure. At any rate, you typically leave the original engine harness in the car alone and use a new fuse block and relay(s) to power the new fuel injection system. This leaves any original sensors and such alone so the original dash still works. At most, you change the ignition feed from a resistive wire to a straight power wire capable of powering the new ignition system.

**Money pit** · 10-19-2015

I am new to this site and was excited to see that someone is also transplanting from a 1987 van. I am doing the same thing except it is going into a 1958 Dodge pickup. I'm just getting started on pulling the engine and transmission out along with the necessary wiring and plumbing. I found the ECM under the seat and traced it through the engine compartment to the firewall side of the fuse panel. Do these connections unplug in some fashion or is it necessary to cut the firewall to preserve the connections? I would like to use the fuse block and parts of the dash wiring harness inside the truck. Where is the best place to mount the ECM? Any and all help is much appreciated.
thanks

**fastacton** · 10-19-2015

Originally Posted by Money pit

I am new to this site and was excited to see that someone is also transplanting from a 1987 van. I am doing the same thing except it is going into a 1958 Dodge pickup. I'm just getting started on pulling the engine and transmission out along with the necessary wiring and plumbing. I found the ECM under the seat and traced it through the engine compartment to the firewall side of the fuse panel. Do these connections unplug in some fashion or is it necessary to cut the firewall to preserve the connections? I would like to use the fuse block and parts of the dash wiring harness inside the truck. Where is the best place to mount the ECM? Any and all help is much appreciated.
thanks

Everything should unplug in some way shape or form. Just take your time and you'll find all of the connections.

**1project2many** · 10-19-2015

ok So is there a wiring schematic specifically for that bulkhead?

Sorry I didn't get back to this sooner.

Each circuit in a GM vehicle is numbered. There are diagrams available which show the bulkhead connector and identify each terminal in the connector by its respective circuit number. The bulkhead connector is "C101" in GM terms. I've attached an example of a diagram of a C101 connector (sorry, not for a van). These diagrams are typically found in the electrical manual which was a very different book than the service manuals. I found a link to a help site (justanswer.com) that appeared to show a diagram from a '92 van for someone with a question about a horn fuse but when I tried to view the site there were no images. Maybe it's something in my browser.

I also looked through my service information but I currently do not have an early fuel injected G van diagram.

Some examples of wiring manuals:
http://www.faxonautoliterature.com/1...al-P14388.aspx
http://www.ebay.com/itm/1989-Chevy-G...-/360318740344

Autozone might have pinouts for C101. They do have some wiring diagrams and other info for the DIY guys. You might try a range of several years.

Also, most of the circuits in that plug are for lights, gauges, etcetera. You could use the remainder of the circuits for your project but if you've already got lights and gauges wired then its redundant. It's not the sexiest connector if you're building a show car...

**Money pit** · 10-24-2015

Thanks. I was able to disconnect the firewall plug from the fuse block by scraping away the waterproofing and removing a screw that held the 2 parts together. I then removed the fuse block by removing 2 screws that mounted it to the firewall. Now to sort out the wires.