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Discussion Starter #1
I recently bought a 1998 916 that was being parted out. I got to the point where I could start it this weekend however it blows the 5 amp fuse back at the subframe the second you turn the engine start switch on. I can hear the fuel pump running and I believe the injectors are firing because I pulled the plugs and they had fuel on them. The bike didnt come with a ECU or chip but I sourced both of them from a reputable site and ended up with an ECU from a 996 and a FIM chip. I am kind of stumped, what would be the next troubleshooting steps I should take? I was going to pull a spark plug wire and verify spark but I am fairly certain the spark plugs arent firing.

Thanks,
David
 

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If I remember correctly, the 916 and 996 don't share the same ECU. (To be sure, check the Desmoquattro Performance Handbook.)


I recently bought a 1998 916 that was being parted out. I got to the point where I could start it this weekend however it blows the 5 amp fuse back at the subframe the second you turn the engine start switch on. I can hear the fuel pump running and I believe the injectors are firing because I pulled the plugs and they had fuel on them. The bike didnt come with a ECU or chip but I sourced both of them from a reputable site and ended up with an ECU from a 996 and a FIM chip. I am kind of stumped, what would be the next troubleshooting steps I should take? I was going to pull a spark plug wire and verify spark but I am fairly certain the spark plugs arent firing.

Thanks,
David
 

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The fuseholder and the wires to it on my 916 overheated and melted a little, even though the fuse was OK, it could be that the wires have through the melted the plastic insulation and shorted together?
 

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Discussion Starter #4
Prior to purchasing the computer I verified from a forum and then with the site I purchased it from that it would work with the 98 916. Apparently they switched over between the two different fuel injection computer during the 916, but the older models use the same as the 996.

I did peel back the wires behind the fuse holder up to where they meet the big wiring harness and they didnt show any signs of being overheated. Its hard to tell from tracing the wiring harness but what is this fuse protecting, or where are these wires going to/from?
 

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Here's a tip for finding shorts, (the back yard way) what does that fuse power? find all things it powers and start disconnecting them, when all that is powered by that fuse is disconnected then install a new fuse, turn key on and start plugging stuff back in, when fuse blows you found either the culprit or at least the wires leading from what you just plugged in to the fuse that may be a problem. Hope this helps!:D
 

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Prior to purchasing the computer I verified from a forum and then with the site I purchased it from that it would work with the 98 916. Apparently they switched over between the two different fuel injection computer during the 916, but the older models use the same as the 996.

I did peel back the wires behind the fuse holder up to where they meet the big wiring harness and they didnt show any signs of being overheated. Its hard to tell from tracing the wiring harness but what is this fuse protecting, or where are these wires going to/from?
The 'Computer' should be compatible just the Eprom is not.

IIRC the 5a fuse protects the one of the engine management relays (underseat) the 20a fuse protects the other relay plus fuel pump.

I can put up or email a wiring diagram if you want.
 

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Discussion Starter #7
I grabbed the wiring diagram from the user manual on the ducati site for the 748, I believe it is the same. Traced it to the relay like DukeDesmo said. I pulled the relay and tested it with a test lamp and it turned out ok. Thinking maybe the relay was stuck I tossed it back in there, gave it a go and still blew the fuse. I know that the the relay feeds into the 4 and 35 pin on the computer. But not sure the best way to test it from here. Should I continuity test from the relay out to the computer connector? Could it be something in the computer blowing the fuse or before? Lastly, the bike came without a computer and I assume the grounding strap that goes from the connector attaches between the mounting nut and computer so it is touching the computer case, correct?
 

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Discussion Starter #8
I pulled out my continuity meter and started testing. I confirmed that the relay terminal 87 goes to 35 on the ECU connector. Then I found there was continuity on the ECU between 35 and 34, which goes to ground, 35 and 17 which goes to ground and 35 and 16 which goes to a bunch of sensors including water temp, air temp, air pressure, throttle position, and the diagnosis connector. So I believe the problem is probably somewhere in those connectors. Does my logic make any sense? Are any of those connectors more likely to fail then others? Are there any tips about how to troubleshoot these connectors?
 

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Discussion Starter #9
So I started going through sensor by sensor and testing the continuity between pin 16 on the sensor connector. I also would test if that pin on the sensor connect would go to ground. The only wierd thing I found was on the air pressure sensor pin 16 went to the middle pin instead of the pin on the left. I assume this is just a variance between wiring diagrams. In the process I couldn't see any obvious exposed wires. Is there any possibility I am on a wild goose chase and that the real problem is something common like the fuel pump or regulator? Are there any other tests that I could do to confirm that it is a bad computer?

Thanks,
David
 

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Discussion Starter #10
I just wanted to give everyone an update on the resolution. I got another computer from Gotham Cycles, sent for free, and it no longer blew this fuse. I had a problem with the fuel pump not running but I re-seated the chip in the ECU and it started up perfectly. Hopefully this can help someone at sometime, thanks for all the suggestions.

David
 

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As a follow-up to DukeDesmo's post:

There are two versions of the 1.6M ECU.

Weber-Marelli IAW 1.6M ECU
One injector/cylinder: 748, 916 Biposto, 916 Senna, ST2

Weber-Marelli IAW 1.6M B1 ECU
Two injectors/cylinder: 996 Biposto, 996S

The IAW 1.6M uses a crank timing sensor at the cam jackshaft whereas the 1.6M B1 ECU takes it's timing firing points from the crankshaft.

This ECU version can be converted to run the 1.6M ECU models (748, 916 Biposto, 916 Senna, ST2 ) if the Ultimap UM222 (or UM232 chip) for the 996 single injector conversion is installed and remapped.
 
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