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> Just want a confirmation on power at relay (4-pin) #1 and #3
Downerman
post Apr 23 2019, 07:16 PM
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So just to be clear. With the Key on.... On the white four connector (Pulled off) on the relay board, Pins I and III. I have 12V+ which means I'm carrying and confirmed 12V+ at the ECU plug on pins 16 and 24 from white 4 connector pin I . In addition Pin 19 on the ECU also has 12V+ from white 4 connector pin III - WITH KEY ON.

Whats happening is I'm not getting a ground from pin 19 ECU back to 4 wire connector on relay board, number III, to pin 86 of the fuel pump relay, as to flip the relay and give me that 2 second pop of the fuel pump. If I take a small wire on the fuel pump relay #86 and ground it I have power on main cabin connector/Relay board pin 13...AKA fuel pump. All relays tested (headlight trick). Using one of the docs on Jeff's site "Porsche 914 Fuel Pump Troubleshooting" and I fail #12 which tells me I have a faulty ECU. Mine was beat... car was a basket case and now fully restored. Got a used one and same issue. Continuity is perfect everywhere - New Bowsley wiring harness (Engine area). I will spare your the other 21 steps but I pass them all except power to the dang Fuel Pump....cuz #87 never get's the signal from III

Here's #12:
12 Test: ECU control circuit
Key off:Test continuity from Pin III on white 4 pin connector plug at Relay Board to ground (white plug harness un plugged from Relay Board. ECU harness plugged into ECU).
Key on: Continuity to ground for 1.5 seconds = good ECU control cuircuit.
Key on: No continuity to ground for 1.5 seconds = faulty ECU control cuircuit
(The ECU grounds Pin III of the white 4 pin connector on the Relay Board to run the fuel pump for 1.5 sec. at key on)

I'm just trying to understand why I have 12V on III with key on. Which means 12V to pin 19 ECU and I don't want to fry something.

Dave
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Posts in this topic
Downerman   Just want a confirmation on power at relay (4-pin) #1 and #3   Apr 23 2019, 07:16 PM
Downerman   So just to be clear. With the Key on.... On the...   Apr 23 2019, 07:20 PM
Minerva's 914   What is the failure? Fuel pump not working, won...   Apr 23 2019, 08:35 PM
Downerman   What is the failure? Fuel pump not working, won...   Apr 23 2019, 08:52 PM
SirAndy   If you jumper the pin to ground like in the image ...   Apr 23 2019, 08:59 PM
Downerman   If you jumper the pin to ground like in the image...   Apr 24 2019, 10:11 AM
SirAndy   So on that pin III of the relay board, it's co...   Apr 24 2019, 11:35 AM
Downerman   So on that pin III of the relay board, it's c...   Apr 24 2019, 08:27 PM
SirAndy   Scratch that, looks like III is connected to 86, n...   Apr 24 2019, 09:05 PM
SirAndy   Scratch that, looks like III is connected to 86, n...   Apr 24 2019, 09:21 PM
SirAndy   Holy crap, i never noticed this, but look at 85/86...   Apr 24 2019, 09:09 PM
Spoke   Holy crap, i never noticed this, but look at 85/8...   Apr 25 2019, 05:21 AM
Downerman   [quote name='SirAndy' post='2708459' date='Apr 24...   Apr 25 2019, 08:00 AM
Spoke   Excellent information guys, thank you. I'm j...   Apr 25 2019, 08:19 AM
jcd914   Actually you are chasing a problem that doesn...   Apr 24 2019, 09:33 PM
Downerman   Actually you are chasing a problem that doesn...   Apr 24 2019, 10:13 PM
jcd914   Actually you are chasing a problem that doesn...   Apr 24 2019, 11:12 PM
jcd914   Just as a follow-up I unplugged the FI harness fro...   Apr 24 2019, 11:49 PM
Spoke   ...If I take a small wire on the fuel pump relay ...   Apr 25 2019, 08:25 AM
Downerman   ...If I take a small wire on the fuel pump relay...   Apr 25 2019, 10:14 AM
Downerman   Third ECU..... it all worked. Now I'm headed ...   Apr 25 2019, 08:41 PM


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