Just want a confirmation on power at relay (4-pin) #1 and #3 |
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Just want a confirmation on power at relay (4-pin) #1 and #3 |
Downerman |
Apr 23 2019, 07:16 PM
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#1
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Member Group: Members Posts: 168 Joined: 23-April 09 From: Monterey County, California Member No.: 10,296 Region Association: None |
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 |
SirAndy |
Apr 24 2019, 09:09 PM
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#2
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Resident German Group: Admin Posts: 41,636 Joined: 21-January 03 From: Oakland, Kalifornia Member No.: 179 Region Association: Northern California |
Holy crap, i never noticed this, but look at 85/86 on the earlier relay boards for that same relay!
(IMG:style_emoticons/default/headbang.gif) Attached image(s) |
Spoke |
Apr 25 2019, 05:21 AM
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#3
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Jerry Group: Members Posts: 6,978 Joined: 29-October 04 From: Allentown, PA Member No.: 3,031 Region Association: None |
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Downerman |
Apr 25 2019, 08:00 AM
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#4
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Member Group: Members Posts: 168 Joined: 23-April 09 From: Monterey County, California Member No.: 10,296 Region Association: None |
Holy crap, i never noticed this, but look at 85/86 on the earlier relay boards for that same relay! It appears to be a typo on 2nd drawing as the PCB layout is identical. I'm going by the schematic below which shows the 86 pin next to the 87 pin. Excellent information guys, thank you. I'm just scared because the original ECU that came with the car was beat to begin with but when I tried it I never got the ground from 19 to blip III and cause the 2 seconds of Fuel Pump. Got another ECU from a source out here in the bay area and the same dang thing happened. I was beginning to think that two ECU's with the same issue was more than a coincidence. Again, testing 22 steps off Jeff's Bowlsby's web site. Each time telling me I had an ECU issue. Well my source has shipped me three more ECU's to try. I did not want to be blowing these suckers up somehow and because I was seeing that 12V at III with key on I was thinking down the harness from that III to 19 on the ECU and perhaps smoking something. Yeah with respect to that spec being whacked the Fuel Pump Relay. I saw that and was just more confused. I'm going to also call my source today as they have a running 914 in the house and just confirm that 12V at III. Will feel so much better than plugging in these three ECU's I just got in yesterday. |
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