I have a 96 Del Sol that was originally a auto/D16Y7 car that now has a manual/B16A and I am having issues blowing the 15 A ECU fuse. I have searched and completed RonJ suggestions of disconnecting the main relay, ECU, IACV, fuel injectors, EVAP purge solenoid valve (not installed), and the O2 sensor and I keep blowing the fuse when the anytime the main relay is installed and the key is turned to the ACC position. I have tested the relay as per the manual and even swapped it out with other tested relays with the same results. The fuse only blow when the main relay is installed

The engine is a ODB2 B16A that I have installed a unmodified B16A3 harness out of a 96 Del Sol and the ECU is a JDM P30 with a conversion harness. The fuel pump will only turn on when you jumper the #4 & #5 wires at C425 under the dash. Looking for anything else to check as the engine harness is not pinched and is routed exactly as it was from the factory.

Any help is appreciated.

Thanks

 

Unplug the equivalents of C101, C130, and C116 to see if the 15A hood ECU fuse is prevented from blowing.

https://honda-tech.com/honda-civic-d...997-a-3266459/

 

Checked, C101 & C116 it still blows, not using C130 (2-wire crank sensor?) but I did figure out that the problem is within C103 (14 wire) connector. Is there a break down of the pin out of this connector?

 

Is C103 the junction connector?

 

Yes, this is the offending connection that is currently causing me grief.

 

That looks similar to C101 for 96-98 Civics. Are you saying that unplugging C103 prevents fuse 31 from blowing?

96-98 Civics have two junction connectors downstream of C101. Same for OBD2a Del Sols?

 

Yes, unplugging "c103" at the shock tower keeps the fuse from blowing. I am getting the connector number from the 96 Honda ETM which shows the C101 to be the four wire just below the 14 wire connector. According to the book the c103 connects to the c404 plug that goes into the ECU. The c101 just goes straight to the ecu in the c406 plug. The manual is ok but it doesn't show in one picture the pin out.

 

What makes you think that the short is inside C103 versus downstream of C103? Try unplugging the downstream connectors one at a time.

 

No, I wasn't thinking the short was in the connector just curious for a written break down of the pinning order.

So, I have been able to locate the short associated with the VTEC pressure switch. I have checked the continuity of ground(black) wire it is good and I have checked the blue/black wire and I do not have a short to ground in the harness and the voltage is present on the correct wire when unplugged. So I figured I had a bad sensor and threw another used sensor I had in real quick and received the same results. Just pulled both sensors over to the workbench to see if I can test them to confirm that both have failed before I run out and buy another.

 

I checked both switches and they test good according to the manual so what am I missing?

 

Focus only on the Yel/Blk wire(s), and try unplugging downstream connectors

 

Sorry, I must have missed something but what yel/blk wires? The only yel/blk wires I see are the common wire on the injector plugs and then the 8 that head into a dead plug on the drivers side by the brake and clutch master cylinders. How does the yel/blk wire work into the issue with the pressure switch?

When you turn the ignition switch to position II the blu/blk wire is feed 12v where it loops in the pressure switch over to the blk wire which is straight to ground at the thermostat housing and then over to the c126 connector which will result in a short every time.

 

There should not be positive battery voltage on the BLU/BLK wire at the VTEC Pressure switch. It simply supplies the ECU with a ground when the oil pressure is above 50 psi... closing the switch and creating a ground point at the thermostat housing for the ECU.

Positive battery voltage shorting to ground is what pops fuses... I would be focusing on positive voltage wires as RonJ suggested... YEL/BLK are the obvious ones. Also look for wire harness damage: chaffing, pinched or crushed wires, etc.

 

--Hood fuse 31 blows after you turn the key to ON(II), right?

--Unplugging the main relay or C103 prevents fuse 31 from blowing, right?

If you agree, your own test results point to an electrical short downstream of the main relay and C103 in the fuse 31 circuit. The fuse 31 circuit downstream of the main relay and C103 consists entirely of Yel/Blk wires. Therefore, all of your focus in fixing the problem should be on locating an electrical short in a Yel/Blk wire in the downstream fuse 31 circuit.

Step 1: Uncap the junction connector (dead plug mentioned above) to see if it prevents fuse 31 from blowing.

 

So the problem is in the C103 connector with the yel/blk as you suggested as you can see from the crudely marked up picture. We have a yel/blk on the body harness connecting to the blu/blk connector of the pressure switch which is the cause of short. I traced the yel/blk back to the ECU and it is feeding off the AGP1 & 2 connector in slot A11 & A24. So much for this harness making things plug and play as I really didn't want a rats nest like the one I removed.

 

What makes you conclude that the short is "in" C103 as opposed to in the circuit downstream of C103?

 

According to JRCivic post above the blu/blk is only supposed to feed the ECU a ground signal and instead of providing that signal to the ECU it was being feed a 12vt signal from the ECU at the connector. If you follow the yel/blk to the ECU it connects at A11 which is incorrect for a VTEC pressure switch which connects at C15. Upon checking the harness at the ECU there is no wire present at C15. My major problem is that I have a properly wired factory engine harness that I need to adapt over to a body harness that is not wired for VTEC.

I have de-pinned the blu/blk wire at C103 and it has stopped blowing the fuse, and the fuel pump has started operating correctly but the VTEC components are now completely disconnected. At this point I am just trying to make the car attempt to start and I can now confirm that I now have fuel system pressure.

 

The wire harness is obviously not pinned properly to the ECU and likely other components. In addition, the VTEC pressure switch seems to be stuck closed to blow fuse 31.

You need to get your wiring mess straightened out. Then go from there.

 

VTEC wiring does not exist on the chassis harness of the '96 Del Sol S chassis... it has to be added.

Since you have discovered an obvious wiring continuity issue at the passenger side shock tower junction, I suggest you FIRST check continuity and voltage/grounds for EVERY sensor on the engine. Second, select some open/unused wires from the automatic plug and use those for your VTEC solenoid and pressure switch... moving them from that plug on the chassis side to two open pin locations in the plug you have pictured. Obviously, you will have to re-locate your BLU/BLK wire on the engine harness side... I suspect after you pin everything out, the number of wires you will have to relocate will be minimal. Just make sure.

In short, check continuity between ECU and all plugs on the engine (plugging in all possible plugs at both shock towers between chassis harness and engine harness)... MAP, TPS, all four injectors, IACV, IAT, ECT, Distributor, Knock, VTS, VTP, VSS, CKF, EVAP/Purge. Then pick two unused wires related to the automatic transmission between the ECU and passenger shock tower chassis plugs... move them to the VTS and VTP pin locations at the ECU plugs and connect the other end of the wires to your big plug pictured opposite the GRN/YEL and BLU/BLK VTEC related wires.

Then, crank it and go drive.

 

I have a 1998 honda accord that keeps blowing the acg fuse have spent 2 weeks so far trying to track down the short. Had melted wires connected to the main relay connects so I replaced them and soldered connections. Issue is still present. I have sense made a jumper with two mail ends on a piece of wire so that I could supply power to each individual circuit that recieves power from the acg fuse. None of the circuits cause the fuse to blow except the pin that has 2 yellow with black striped wires that go to the ecu. I since disconnected the ecu and fuses still blow. When relay is plugged in fuse only blows when car it turned over but when I direct connect the power to the ecu wire it blows immediately. I even ran a direct line from battery to the main relay connect with an inline fuse to bypass the green and white power wire but still blows. I have narrowed the issue down to the wires from Main relay connector to the ecu I believe but am not positive a since it blows even when not plugged into the ecu. Any insight or guidance is desperately needed!