Got this problem with my car having no power to the ecu and the fuel pump not priming before starting. Cant think of what else to do, all the symptoms point towards the main relay. Ive changed that out twice with a OEM(RZ-0132) one and a aftermarket one(RZ-0159. Ive traced all the grounds, power wires from ECU A25/B1 to main relay and no breaks. Checked for power A25 and the main relay and their good. This test eliminates the possibility of having a blown fuse, checked them anyways and they are good. Swapped ecu's and thats not it either. Im bummed out, any ideas?

 

have you checked the 15 amp fuse under the hood? actually pulling it and checking.

 

I've pulled them and checked them with a volt ohm meter, all good.

 

I would lean toward engine and chasis grounds. Had something similar on a IS300 and was a engine ground. I know you already said you checked grounds,but couldn't hurt to check one more time. What year car and engine? I can pull up schematic if I have info.

 

Checked that too. This is in a EG hatch with a B16, ground for the ecu is located on the termo and thats just one. Whole thing doesnt make any sense. Solid cell, one click after turning the key, no fuel pump sound. Only reason I know the ECU isnt getting any power is because the S200 led doesnt come on.

 

Bad ignition switch..... just an idea..

 

There are 3 fuses for the PGM-FI Main Relay, have you checked them all.

Sorry, I do not have the fuse # for an "EG", but you can test at the PGM-FI Main Relay.

One lead, [probably a white/black] will be hot at all times.
One lead, [probably a yellow/green or black/yellow] will be hot in run and start, the fuel injector relay output, [probably a yellow/black] should also be hot if relay is working.
One lead, [probably a blue/white] will be hot only during cranking to start.

Also make sure the black lead(s) have a good ground, [continuity to chassis].

Testing at the PGM-FI Main Relay will give you a better idea of what may be wrong. 94

 

I've checked every fuse in the car, even the ones that have nothing to do with the problem I'm having. Getting power at the main relay connection also. It's something that im over looking, just haven't found it yet.

 

Have you checked the 12V+ inputs to the ECU/ECM from the PGM-FI Main Relay, [injector relay], if there is no 12V+ from the PGM-FI Main Relay to the ECU/ECM there will be no ground output from the ECU/ECM to the PGM-FI Main Relay, [fuel pump relay].

You said, " Getting power at the main relay <<connection>> also" there will be 3 leads, [<<connections>>] at the PGM-FI Main Relay that have power, [inputs] 2 leads that have power, [outputs] the injector relays output is constant as long as ign. is on, the fuel pump relay has output only if ECU/ECM is supplying the ground for the relays coil.

Make sure that you have power on all 3 inputs, 3 of the leads should test as hot when ign. switch is on, 2 inputs and 1 output, the 3rd input is only hot during cranking to start.
Then make sure that the fuel injector relas output is getting to the injectors and the ECU/ECM, [IGP1 and IGP2] these leads to the ECU/ECM should be the same color as the power leads to the injectors, [probably yellow/black] 94

 

Figured there was only one since A25 and B1 are IGP1&2. I'll check it out a little later, weather is taking a turn for the worse tonight. Thanks for the help fcm, I'll post result asap.

 

Only got one source of power and thats coming from the yellow/white wire going straight to the underhood fuse box. This is the one thats always hot. Ignition switch has power too, figured I'd check that as well. Only thing I can think of is a bad underhood fuse box. Also checked wires coming from the fuse box to the ECU and main relay and no breaks. Total b/s, did I miss anything?

 

Was the inside fusebox that was bad. Hope no one ever goes though this issue. Thanks for the replys and help all.