3.2 conversion, DME wiring to fuse panel

[chrisf]

3.2 conversion, DME wiring to fuse panel

I’m installing a 3.2 into my ’76, and need a little more info concerning the wiring of the DME into the existing fuse panel. I have read and been following Modification which has been very informative, but I think my ’76 differs a little from the ’77.

In Marc’s thread (pic shown below) he talks about taking the black wire from one of the DME bundles (green and purple arrows) and connecting it to the 15 terminal (coil) via the 16amp (red) fuse in the front panel: “On the ’77, this wire was connected to the bottom of fuse#3, on the middle block”

I believe this to actually be fuse S16 for the ‘77 per the factory current flow diagrams. (I came to this conclusion by comparing the factory’s ‘76 diagrams to that of my fuse panel and the wires coming in the top and out the bottom of each fuse block. Fuses are counted from the front of the car, starting with 1.)

If this is true, then by referencing the pic from Marc’s thread, shown below, the DME wire receiving current flow when the coil is on (terminal 15) is actually connected to the bottom of S16, which, following the factory’s current flow diagram, is for power to the fuel pump relay, J16, also shown below.

Marc's photo:

photo from factory current flow diagram, '77:


Looking a little further into this I see that when the ignition is switched on power for terminal 15 (from D: ignition/started switch, red/black wire) flows to connection T6f and branches: to tach & other gauges, and to the top of fuse S12. Reference the yellow squares numbered 63/62.





S12 & S11 share the same current in, shown by the thin black line as being “internally connected”. (In the preface to the factory current flow diagrams, it states: “The thin black lines are not actual wires but internal connections”.

Following the leads back 62/63, current flows from the top of S11 (unfused) to the top of S16. Marc made is connection on the other side of this fuse I believe.

Looking even further at the diagram at N: ignition transformer (this is the coil) is connected to the N15:High tension ignition unit, which has a red lead the runs from connection T2a, which receives current flow from the top of S11, unfused. Summarizing, fuse S11 receive current in from S12, the leads from the top of S11 flow current (unfused) to S16 (fuel pump relay) and to connection T2a, which goes to the coil.



So far, am I reading this correctly?

[chrisf]

When examining the current flow diagram for the ’76, I see the same red/black terminal 15 wire running from the ignition switch into the top of S12 (and subsequently top of S11, this time following 52/53)




Unlike the ’77 (whose S16 fuel pump relay fuse ran from the top of S11), the red lead from the top of S12 runs over to the fuse for the fuel pump relay, but here it is shown as S21. Here is where I get confused. My front fuse panel has only 18 fuses. I don’t know where fuse S21 is. I know fuses 22-24 are on the rear panel, but I can't find fuses 19-21 anywhere on my car, And I can't even find fuses 19&20 on the factory current flow diagram.

I have confirmed that I have the red wire running from the top of S12 into a bundle going right up to the pump relay, but It doesn’t seem to be fused.

I don’t want to wire up the black wire to the DME unfused. I could run it from the bottom of S12, but this fuse is a 25amp fuse. I don’t want to fry the DME. I could run it from the bottom of S11 (which is a 16amp fuse) but this fuse also provides current to the stop light switch, back up switch, and is wired up with the emergency flashers. Drawing to much current could blow this fuse.
Anyone have any experience with wiring up the 3.2 into a ’76 and run into this issue? Or does anybody have any suggestions?

[chrisf]

forgot to include picture of this S21 fuse I can't find:



J16 is the fuel pump relay.

[marcesq]

Chris,

I counted from left to right, not from front of car, probably a mistake. I apologize if this threw you off. As I recall, all I wanted to do was mirror the '89 connection for fuse size and provided power upon start up, and while the key is on.

Any such fuse on the '76 panel should work. Why don't you use the same fuse that your car uses to power the #15 terminal of your coil (can't remember if you have a CDI or coil)?

Hope this helps.

Marc

[chrisf]

Marc, no apologies necessary. your documentation has been a great help.

I think I had both a CDI (6pin) & a coil.

I've had a little time to thing about this. My fuse panel doesn't have a fuse for S1. It doesn't have any lead going into it or out of it:



In addition, the current flow diagrams for the '76 doesn't list an S1, just S2-S18 for the front fuse panel.

I think I might jump from the S11/S12 input (red/black wire from terminal 15 on the ignition switch) to the S1 input. The connect the black wire from the DME harness (red/green & black combo) to the out put of S1, and stick a 16amp fuse in there.

As far as the second black wire (bundled with the black/vio wire, going to tach) I'm just hooking to the bottom of S11, as you have done. Those are the same for '76 & '77.

I appreciate the additional help Marc. Let me know if you have any additional thoughts on this.

~Chris

[marcesq]

That should work. The front end of your car sure cleaned up nicely.

Let me know if you need any other help.

Marc

[chrisf]

Hey Marc:

I've just thought of something else. on my '76 I had the CIS meter switch. This switch cut the fuel pump off (through the relay) when the engine did not run, even though the ignition switch was "on".

(Originally, the fuel pump would always run. I found a connection in the back that was open. I made that connection and it fixed this condition. I did the test of opening the meter plate, and the fuel pump would run, etc...).

Now, with the 3.2 installed, this meter switch (or the connection for the switch, in the back) will be open (like when I originally got the car). Is this a correct assumption? Was there something you did on your car to ensure the fuel pump only ran in the correct condition, i.e: when the starter is engaged or when the engine is actually running, and not when the ignition is in the "on" position?

~Chris

[chrisf]

bump for any experience/info with this pump issue

[mikedsilva]

ok, I know this is an OLD thread, but wasn't able to find exactly what I was after...

I've just installed a 3.2 into a 79 SC body.

Couple of things:
1 - I'm not happy with how the pump is working.
2 - it runs but doesnt stop, unless I disconnect the battery.

1 - I've read where people are not using the yellow wire from the DME harness.. if that's the case, then doesn't that mean that the pump is turning on as soon as the ignition is on? Nothing really wrong with that I guess, but I don't think that's how the 3.2 is meant to work.
I'd lke to tap the yellow wire from the motronic harness, to the yellow wire in the starter circuit. My understanding, is that when you turn the key to the start pos, then the yellow wire is energized, which activates the fuel pump relay next to the ecu, then it puts power through the red/green fuel pump cable to power the pump directly. Then if the engine stops, the pump will also stop. '
Just not sure where to find access to the yellow starter wire, in the front compartment??


2- Runs all the time even with key off. I think I have the coil wire connected to the wrong terminal in the fuse block. (electrics are not my strong suit). I thought it only needed to be fed to a fuse that had power when the ignition was on.
Looking at Marq's website, he says The 3rd harness (yellow arrow) has 4 wires. 2 blacks, a yellow, and a black/violet. You have to find the black wire (blue arrow) that connects to Pin 5 of the DME Relay Socket with an ohm meter, and connect it to the bottom of fuse #8 on the middle block.

So I changed where I connected the black coil wire, to the one that Marq suggests. And lo and turning ignition off, and the engine stops. This is pulling power from the backup light circuit. So to confirm, this is OK to use?

[marcesq]

Can't believe that I am still getting pinged on this . . . glad the information has lasted this long.

Mike,

You can use any fuse that receives power when the key is turned to the ignition position as opposed to the starting position. The power draw is minimal since you are providing the small amount of current that the relay uses to activate the high level circuit.

Engine looks great . . . brings back some great memories.

Marc

[mikedsilva]

Originally Posted by marcesq

Can't believe that I am still getting pinged on this . . . glad the information has lasted this long.

Mike,

You can use any fuse that receives power when the key is turned to the ignition position as opposed to the starting position. The power draw is minimal since you are providing the small amount of current that the relay uses to activate the high level circuit.

Engine looks great . . . brings back some great memories.

Marc

Marc
your webpage is a great source of info!
The first fuse I tapped to go to the coil, resulted in the engine starting fine, but continuing to run even after the key was off and removed!

I think I was using a fuse from beginning of the block (towards rear of the car).

As for fuses that supply power in the Starting Position.. which are they? Would be handy to supply 12v to the yellow wire in ecu harness (to engage the pump relay).

[marcesq]

Mike,

I do not recall if I changed anything for the fuel pump wiring. I installed the 3.2 fuel pump in the same location as the 2.7 pump and used the same harness.

[stubble88]

Restarting this.
I can’t get my fuel pump to come on. It does work I tested it.
I have an 1983 harness and panel.
I’m confused about the use of the red/green wire.
I also do not have any power to my #30 fuel pump relay.
The coil does have power.

[marcesq]

Still getting pinged on this.

Fuel pump wiring should not have changed from the original wiring. If it's not coming on, then make sure the ground from the pump to the chassis is good, and trace the + wire from the pump to the fuse panel. If there is no power to the fuel pump relay, then there is problem with the wire in the car's harness that provides power to the relay. I can not recall the routing of the relay battery power wire, but it gets power when the ignition switch is in both on and starting positions.

Red/green wire is not used

Hope this helps.

[stubble88]

If I don’t connect the green/red wire the fuel pump does not power.