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Sat Jun 09, 2018 6:50 pm

Hey everyone

I just rebuilt my fi harness and now I'm having an issue. I don't seem to be getting a ground signal (beige wire plastic plug) from the ECM. what does the ecm look for to give the ground signal?

could I just ground that wire ? what would be the side effects from doing that?

thanks for the help

Sat Jun 09, 2018 9:29 pm

I would think Ground is just ground and the control wire from the Driver Transistors of Jetronics D control box would be pulsed positive.
Bosch Jetronics D schematic I would make the ground connection the same as the one grounding the control box.

Sun Jun 10, 2018 8:57 am

cdn_squareback wrote: Hey everyone

I just rebuilt my fi harness and now I'm having an issue. I don't seem to be getting a ground signal (beige wire plastic plug) from the ECM. what does the ecm look for to give the ground signal?

could I just ground that wire ? what would be the side effects from doing that?

thanks for the help
Are you asking about the #19 wire? If so, that wire goes to the front under dash relay to run the fuel pump. With it grounded, it runs the pump anytime the key is in the on position.

Sun Jun 10, 2018 10:14 am

You can try grounding that 19 wire in the engine bay for testing purposes, but I would not drive it that way. One function of that circuit is to cut ground to the pump relay if the engine stops. In an accident, the engine could stop but power still be on, causing the pump to run continuously and possibly dump gas all over.

Sun Jun 10, 2018 10:28 am

I assume Type 3 in question here is a 1971 and I see this wiring diagram showing the fuel pump relay running on a wire from a connector from the Jetronix electronics box. Wire J21 and the fuel pump on G6 are shown in this 1972 Diagram:1972 Wiring.
Here 1971 Wiring Diagram

Mon Jun 11, 2018 5:13 am

Bobnotch wrote: cdn_squareback wrote: Hey everyone

I just rebuilt my fi harness and now I'm having an issue. I don't seem to be getting a ground signal (beige wire plastic plug) from the ECM. what does the ecm look for to give the ground signal?

could I just ground that wire ? what would be the side effects from doing that?

thanks for the help
Are you asking about the #19 wire? If so, that wire goes to the front under dash relay to run the fuel pump. With it grounded, it runs the pump anytime the key is in the on position.

yes, pin 19 at the ecm that goes to the fuel pump relay 85

Mon Jun 11, 2018 5:18 am

Bobnotch wrote: cdn_squareback wrote: Hey everyone

I just rebuilt my fi harness and now I'm having an issue. I don't seem to be getting a ground signal (beige wire plastic plug) from the ECM. what does the ecm look for to give the ground signal?

could I just ground that wire ? what would be the side effects from doing that?

thanks for the help
Are you asking about the #19 wire? If so, that wire goes to the front under dash relay to run the fuel pump. With it grounded, it runs the pump anytime the key is in the on position.

whats the activity of the wire? I imagine it should pulse at key on. what does the ecm look for to send the pulse?

Mon Jun 11, 2018 5:25 am

Danwvw wrote: I assume Type 3 in question here is a 1971 and I see this wiring diagram showing the fuel pump relay running on a wire from a connector from the Jetronix electronics box. Wire J21 and the fuel pump on G6 are shown in this 1972 Diagram:1972 Wiring.
Here 1971 Wiring Diagram

in my Bentley, it shows pin 19 out of the ecm to pin 85 of plug 26 on the fuel pump relay.

Mon Jun 11, 2018 10:57 am

Danwvw wrote: I assume Type 3 in question here is a 1971 and I see this wiring diagram showing the fuel pump relay running on a wire from a connector from the Jetronix electronics box. Wire J21 and the fuel pump on G6 are shown in this 1972 Diagram:1972 Wiring.
Here 1971 Wiring Diagram

The problem with that diagram, and most in the brown Bentley, is there are no real pics of the FI system in them. You have to go to either the "K" manual, or Elfrink to get the diagram needed.

Wed Jun 13, 2018 10:12 pm

Thu Jun 14, 2018 8:01 am

That last Elfrink wiring diagram answers a curiosity question I've had for a long time... on an automatic, where does the red electric AAR wire connect? Answer: Same as the fuel pump connection at the pump relay. Which means it lacks power if the engine isn't running, correct?

Thu Jun 14, 2018 8:22 am

KTPhil wrote: That last Elfrink wiring diagram answers a curiosity question I've had for a long time... on an automatic, where does the red electric AAR wire connect? Answer: Same as the fuel pump connection at the pump relay. Which means it lacks power if the engine isn't running, correct?

I think that is correct. I need to go back through the pin outs.

This was done several ways across sevsral models. In auto 411 and 412....it surreptitiously gets its power through the enyine speed relay which actually pulls its power from the coil.

The non auto 411 412 do it just like the auto type 3 note that Elfrink made.....from pin 87 on the fuel pump relay. That "should" shut off when engine stops. Ray

Thu Jun 14, 2018 8:44 am

Also.....not sure what version of the Bfown Bentley you guys are using but the Pin out/schematic like the one Kanester posted....is on pages 18 and 19 of the EFI section in Bentley.

Yes....wire # 19 comes straight from the ECU to the pump relay. The ECU gets ground from several locations.
#11 is one ground source to the ECU at the main ground bundle. I do not know about the distribition path inside of the ECU and #11 "may" not be the only ground source. But if those ground bundles are not tight.....you can alternately get no run condition. Ray