How does the Diagnostic Port wire up?

Hello!

I’ve got a 1991 Eunos 1.6 Auto.

I’m swapping out the ECU for an MBE ECU as part of my Rocketter build.

As part of this, you need to splice 4 wires in the original loom with wires from the new ECU; RAD FAN, FUEL PUMP, IGNITION 12V and TACHO.

When I test for continuity of the Fuel Pump wiring at the diagnostic box, I get no beep even though i’m 99% sure I have selected the correct wire ending at the ECU Connector.

This is the same with the fuel pump relay attached/not attached.

What could be causing this?

Thank you in advance!

Andrew

Could you explain exactly how you are testing for continuity please???

This chap,

I used to chat regularly over on MX5Nutz, he did this swap and is very knowledgeable. No harm in an enquiry? He prefers using his FB page I believe. Only use the contact form for actual work being booked in. :crossed_fingers:

Barrie

just realised it was an auto to manual swap rather than to Rocketeer, would the issue still be the same? :thinking:

2 Likes

Well, I am also doing the auto to manual swap, so he can probably help me in lots of ways! Thank you :smiley:

Hello, thanks for the reply :slight_smile:

I’m a complete beginner so I followed an example given to me by a rocketeer builder - he told me disconnect the fuel pump relay, and place a probe at the diagnostic end of the f/p wire and then on the ECU connector end.

No matter what I did, I couldn’t get the fuel pump continuity test to make the multimeter beep, in fact I couldn’t get anything to beep at all.

I did connect the probes together to check the beep function was working and it was fine.

Hmmmmm, I’m not familiar enough with it to picture exactly what you mean. I’ve not heard of beeping continuity testers before but it seems a reasonable idea as long as the beeper is set to allow some resistance, I’m not sure why you are disconnecting the relay if you are testing continuity within a wire leading from the relay to the ecu.
If you are testing for continuity through a component, that’s not something I’ve ever tried and have no idea about. If I were testing a fuel pump, I would be tempted to briefly connect it to a battery to see if it works.