CEL Confusion

[SwiftE30]

so two days ago i went to my car and it had a dead battery. Once i put a charge to it it started up just fine. And my CEL was on when ignition was in the on position.

I went to start it today and the battery was dead again, so i grabbed a battery from my other car and tried to start it. It just cranked and cranked and cranked. AND, my CEL was not on w/ ignition in on position. It was a charged battery and i had fuel in the gas tank.

It seems like when i switched to the other battery something happened because my ECU isnt getting power, and i cant hear my fuel pump priming.

Any thoughts?

[valleymotorwerks]

Checked your main relay? Could be that it was stuck open and killed the battery and now it's burnt up.

[SwiftE30]

Checked your main relay? Could be that it was stuck open and killed the battery and now it's burnt up.

k i'll check that. i think i might have an extra one around the shop. Its the white one right? is this one possible to jump?

[328ijunkie]

You can jump any relay, the main one is just annoying because it has two outputs

[SwiftE30]

k. i've only jumped the fuel pump relay and that was relatively easy using someones direction and explanation. Any help with jumping the main relay? I'm not really confident in my electrical knowledge and would hate to do it wrong and screw something else up.

[SwiftE30]

anybody?

[Adrian_Visser]

You can't really fuck anything up jumping the relay, it will either work or nothing will happen. Look at the side of the relay case, there is a schematic like this:



The two 87's are the outputs. 30 is the input, 85 and 86 are the coil power and ground.

So if you want power to flow as if the relay were energized you must jumper power at the relay socket from the slot corresponding to 30 over to each 87. Two pieces of wire, cotterpins or my favourite Mcgyver tool paperclips can all be used to do this. It is the same as the fuel pump except two jumpers are needed. Remember the relay socket will be a mirror image of what the bottom of the relay's pin orientation looks like okay.

Just remember your car will not shut off with the key once you do this.

[SwiftE30]

awesome. thanks for the detailed explanation, that realy helps. So for a little update i tried doing the stomp test right before i came in and read this.

after doing the stomp test i got no code back. Check engine light doesnt do anything. This leads me to believe my ECU is not getting any power right?

[SwiftE30]

fuel pump is not priming at all either. just FYI. all signs pointing to my ECU not getting any power. and i dont know if this gives a better indication of what is wrong, but when ignition is in the ON position, my brakelights are on.

UPDATE: jumpered the main relay correctly and there was no change.

i used muy multimeter to check power and sofar i have traced power from battery through each connection to the c101/x20 plug, have power there but i am getting an assortment of reading when poking around in each pin of c101. once i plugged it back in i had power to each relay too.

pin 13 for fuel pump at c101 does not have any power. it reads 0 on my multimeter. this should be powered with ignition in on position right?

where should i go from here? i'm stumped

[SwiftE30]

update: i added an extra ground wire to the ECU and it fired right up. Now im getting a check engine light with no fault codes when i do the stomp test.

any suggestions?

[singh336]

i having the same exact situation, well it's never fired for me yet because its a brand new swap, but i have no power to my ecu either

i tried to ground the outside of the ecu case for jokes to see if that made any difference but nothing,

how did u ground your ecu and to where?

[SwiftE30]

i having the same exact situation, well it's never fired for me yet because its a brand new swap, but i have no power to my ecu either

i tried to ground the outside of the ecu case for jokes to see if that made any difference but nothing,

how did u ground your ecu and to where?

pm'd. I would also check the two power wires coming off the e30 fuse box.