944 No Power At DME Relay

[Deemar]

1983 Porsche 944.

My car cranks with no tachometer bounce and I've traced it back to 0.09 volts on terminal 86 of the DME relay. Since the computer is not getting a full 12 volts with ignition on, it's not turning on the fuel pump.

I've read online this is likely a failed ignition switch, which requires removing the steering wheel, gauges and part of the dash to access. Before I start performing surgery on my car, does anyone know anything else I should be checking? It has been working absolutely fine up until now but I did leave it parked outside for about 4 months. I also replaced the battery last week with a new one since leaving it parked that long killed the battery.

Thanks a lot.

[Tom]

1983 Porsche 944.

My car cranks with no tachometer bounce and I've traced it back to 0.09 volts on terminal 86 of the DME relay. Since the computer is not getting a full 12 volts with ignition on, it's not turning on the fuel pump.

I've read online this is likely a failed ignition switch, which requires removing the steering wheel, gauges and part of the dash to access. Before I start performing surgery on my car, does anyone know anything else I should be checking? It has been working absolutely fine up until now but I did leave it parked outside for about 4 months. I also replaced the battery last week with a new one since leaving it parked that long killed the battery.

Thanks a lot.

You might check the wiring from terminal 86 to the switch and/or bypass the whole relay (with power to 86 from the battery) to confirm it starts that way. You could also check that the switch is getting power. But, yeah, the key switch seems like a real possibility....

[Deemar]

Are you suggesting I get a wire with a spade terminal, connect one end to the battery and push the spade terminal into terminal 86 of the relay port just to check if it starts? I was thinking about checking that but wasn't sure if that would hurt it in any way. I'm pretty sure that would work, though.

If it does work, does that confirm the ignition switch?

[944er]

Check for power at the black wire on the coil with the ignition switch on. It is also directly powered by the ignition switch. If there is power here, and not on terminal 86 of the DME relay, it is not the ignition switch. If both do not have power, it probably is the ignition switch.

[Deemar]

Check for power at the black wire on the coil with the ignition switch on. It is also directly powered by the ignition switch. If there is power here, and not on terminal 86 of the DME relay, it is not the ignition switch. If both do not have power, it probably is the ignition switch.

Do you mean the black wire from this group here? I'm referring to the larger bundle that's connected in this photo.

IMG20260730214914.jpg (5.36 MiB) Viewed 244 times

[Tom]

I think he means right at the coil itself, which is in the front left corner as you lean over the engine bay.

[Deemar]

I think he means right at the coil itself, which is in the front left corner as you lean over the engine bay.

Oh, the distributor? You mean the fat center plug, just pull it off and check it with the multimeter?

[Tom]

I think he means right at the coil itself, which is in the front left corner as you lean over the engine bay.

Oh, the distributor? You mean the fat center plug, just pull it off and check it with the multimeter?

No, the ignition coil -- roughly the size and shape of a 7oz can of Coke. See pic below -- it's to the left of the distributor cap. If you follow the wire from the center of the distributor cap, the other end plugs onto the big center post of the coil. To either side of that center post, there are two electrical wires attached to little threaded posts with a nut -- one green, and one black. That's the black wire he's referring to... If unmolested, there will be a black plastic cover on top of the coil you'll need to remove to get to the wires, which can take some fiddling....

coil.jpg (142.45 KiB) Viewed 231 times

[Deemar]

Check for power at the black wire on the coil with the ignition switch on. It is also directly powered by the ignition switch. If there is power here, and not on terminal 86 of the DME relay, it is not the ignition switch. If both do not have power, it probably is the ignition switch.

My car is completely stock, I bought it from the original owner.
I got the plastic piece off and confirmed there is 11.98 volts at the black wire on the coil. Where do we go from here?
I'm going to try my own research while I wait for a reply but there isn't much information online for these early cars.

[Tom]

Does your car have an alarm? If so, try bypassing it...