Relay Won't Release - on new EFI Install

[Drbraunsr]

New EFI install (Electromotive) with their power module.
Problem: car starts, but when the key is turned off - the engine continues to run. Pull the fuse to stop.

Initially, the car stopped when the key was turned off.
I've changed each of the (2) relays in the power module with no success.
I'm thinking it's being back fed somehow and the coil isn't releasing the circuit.

Not sure what to look at next.

[Drbraunsr]

The wire highlighted is the wire that holds the backfed 12v to not releasing the coil.
I wired it to the first fuse position (I believe it's the power windows slot)

[Jonny042]

Is there any sort of electonic module pulling in the relay? Could be leakage current holding the relay in if it's not a dry contact keyswitch like the diagram.

[Drbraunsr]

The Yellow/Red is pulling from the main fusebox in the frunk. I'm gonna answer that question as no, in my limited understanding. I moved it to another fuse, just to use a different circuit with the same result.
In reading your response, I'm gonna jump it back to the key switch to find out for sure.

[rsscotty]

Can you post a picture and part# of the ECU relay?

[Drbraunsr]

Direct wire to the key -- same result.
The power harness' layout seems fairly straightforward. The only "rogue" wire is the Lt Green to the relay pin 85. It's a ground wire from the ECU to the relay and should drop when the ECU is cut off.
I CAN hear the fuel pump rise a few RPMS about 1 second after the key is turned on.

[Drbraunsr]

Here's two pics. The black Beuler is the stock one provided by Electromotive and the gray I picked up locally when I thought I just had a bad relay.
One pic has the numbers and the other pic has the schematic. The black Bueler looks to have a resistor with the coil ?


The Beuler is a five pin / the gray a four pin, but I don't need the 87a pin (I believe)

[Jonny042]

Perhaps try isolating the issue a bit - try dicsonnecting the wires from the keyswtich and bypassing it with a jumper wire, just to make sure there isn't some other issue. Start with the simplest form of the circuit and start adding wires until you re-create the issue.

[jpnovak]

I would disconnect the trigger point from the ignition. When you connect the trigger to 12V (battery) both relays should click to close the contact. Then release 12V and they should click a second time to open the contact. If not, then there is voltage feedback and you likely have a relay wired backwards.

If so, then your 12V switched supply is not actually switched.

What fuse do you pull to get it to turn off? If the relays are locked one of the fuses may be connected to the wrong terminal(feedback from one relay to the other) and keeping it on. Check one by one with the first test and isolate the wire.

Your wiring diagram shows 2X red/white "Switched 12V" going to a 2A fuse. Where do these go? They can be used to power something but they should not be connected to 12V switched supply or you will get feedback and relays will stay powered on.

['76 911S 3.0]

Does the FP Relay trigger go to the ECU? Does that particular lowside have a 12v pullup on it? If so, that could be causing the backfeeding issue and not allow the ignition relay to de-energize.

As far as the 87 vs. 87a, 87a is connected to the 30 terminal with the relay de-energized, 87 is connected to 30 when the relay is energized. As long as you have nothing going to the 87a circuit, it's not an issue. Just be aware, you will have 12v on the 87a pin even with the key off based on the diagram posted. Just make sure there is no chance that it can short to ground anywhere.

[Drbraunsr]

Jamie - jumped the 12v switching straight off the battery, both relays closed/opened OK
The fuse I pull is off an intermediate terminal block adjacent to the battery for a few higher voltage connections that were off the battery lug.
The 12v Red/White go directly to the ECU for it's main power (in redundancy).

I did dis-connect the alternator to eliminate the possibility of the internal regulator failing and creating a back feed --- bummer, did not fix.

Jayson - the Lt Green wire grounds the coil for the FP and allows the Green wire to provide the 12v to the pump itself

What is interesting, the fuel pump will run for 7 seconds (as designed for priming the fuel rail) and if switched back off - turns off. It's only when the engine starts/runs that the problem initiates.

Thanks to you guys for answering.
I plan on posting the eventual solution to maybe help others.

I'm happy though today, since I got the car registered and off non-op status in CALIFORNIA !
Which is a miracle in itself. I just can't turn the damn thing off so I can drive it ! LOL

[rsscotty]

You could try one of these relays with a diode. I have had same issues with a few cars, either a diode in the alternator light circuit or this diode relay solved the problem. Just make sure you wire like the relay says, 86 is 12v switched feed.

[Drbraunsr]

Absolutely worth a try.
A picture was worth a 1000 words. Thanks

[Drbraunsr]

While I'm waiting for the diode relays to arrive (Friday) - I think I isolated it to the stock FP relay, as Jayson speculated. The FP relay within the Electromotive power module does go back to the ECU via the ground side of the coil. How these relays are back-feeding still eludes me.
As Jamie likes to say, I can't understand it for you. That applies in this case.
I've stopped looking until I try the relays. I'll report back....

[Jack Stands]

Please keep us informed. I think the diode was the difference between the red and black round relays that Porsche used?

[jpnovak]

Some EFI ECUs do ground interrupt to drive FP. Some do high side (+12V) interrupt. Make sure that you are compatible between your ECU and the Porsche wiring. otherwise you will likely feedback across the system.

[Drbraunsr]

The diode relays I bought to go into the Electromotive power module did not solve the problem.

Jamie: the Electromotive gt200 ECU uses a ground interrupt to drive the FP (LtGrn to pin 57).

I narrowed the feedback thru the Porsche relay 1 or 2, not the Elect power module relays.
I read Jack Stands note regarding the round relays black vs red. I had a spare red (911 615 108.01) and swapped it into the 2nd relay socket and FIXED !

Thanks guys for the community effort !

[jpnovak]

Awesome. Glad its working. Happy Tuning.