Please help my electrical gremlins!!!

[Cpt_Impossible]

I have been battling a battery drain for about five months or so now and it is driving me insane...

1990 240sx CoupeRB20DET swap

Right now with everything turned off, it drains the battery at a rate of .01volts every 20 mins or so. Thats without the alarm or anything on and all switches turned off. After 1.5 days it will not start. I havent tested how much having the alarm on shortens the battery life.

I unplugged the alarm and e-fan fuses and no effect.

I unplugged ALL of the fuses on the interior kick panel and it slowed it down to about .01volts every 30 minutes.

The alternator was replaced in hopes that that was the problem, but no.

The battery was tested and found to be in perfect condition (Optima Yellow Top).

The battery was switched with a normal battery and no effect.

The normal battery was at 12.69volts and cold when it was placed in my car. While taking out fuses one by one I ran it down to 12.43volts. I know that this could be considered normal, but I have been trying crap for months and I know the drain will keep going I have run my optima dead numerous times testing this.

Im no pro with the multimeter but I set it to 200m DCA Which IIRC is .2 amps of reading room. IIRC the acceptable normal drain a car does to a battery is less than .03 amps. When I stick this to my negative terminal and battery post and remove the cable fromt he post It spikes higher than 200m and just reads "1" meaning out of range. The only way I have found to get it to stop reading over 200m is to remove:-Eng control Fuse-IGN switch Fuse-Alt Fuse

When those three are removed, the reading is 2 or 3 on the 200m scale. Problem Is that doesnt narrow it down much because between those 3 fuses there is a gob of stuff that is powered. The really odd thing is that when those three fuses are removed, the reading went from 12.44volts to 12.56volts and a few minutes later rose to 12.58volts. The alternator is changed and the battery isnt the problem either. I have inspected the ECU inside and I cant see any visible damage. All of the grounding points seem fine.

I cannot leave my car out on the street without an alarm and am tired of my battery being dead when I go to start it when its left connected. Can anyone help me out here and point me in the right direction. Im about to take it to a shop if I cant get this figured out soon. But I know its gonna take them forever and cost me a ton.

[180fan]

What other devices you have hooked up to this car? Do you have anything hooked up to the constant on the inside instead of the accessory wires behind the dash and so on?

[Cpt_Impossible]

K, I did some more testing. The only thing I have added thats constantly wired is the e-fans and I ruled that out. If I take out the inline fuse it does no good.

I was curious if it was the starter because the way I see it, it has to be something somewhat strong to drain the optima. I disconnected the starter switch wire and the battery to the starter leaving just the battery wires foing to the alt. I redo the removing the terminal test and still get "1"

I removed the alternator wires fromt he battery leavign nothing but the cable itself and still got "1" So that test isnt helping me any either my multimeter is messed up on that setting or I am not using it correctly. I put it all back on and retested the 3 previously mentioned large amp fuses and found that on or off it didnt mattter I get "1 no matter what I do.

So the conclusion I have come to is that the only way to check any change is:A) wait a few minutes to see if voltage goes downB) Plug everythign back in and unplug one by one until the voltage goes back up.

WHAT I FOUND IS....

With everything else plugged in and I mean every fuse and relay back in place. If I take out the "ENG Control" fuse (25A) The voltage startes going up. If I remove that fuse, the voltage goes back down, more rapidly this time, about .01volts per 30 seconds. IIRC this fuse is the ECU. Can someone confirm this? This would suggest to me that maybe my ECU is broken or something plugged in to my ecu is broken. Im thinking it must be the ECU itself or an ECU power is grounded or something because otherwise I think having all of the fuses removed other than this would solve the problem. The things that the ECU controls the power to it controls as the switch, not as the power source.

Any advice? I dont happen to have an extra RB20 ECU on hand at the time.

[Cpt_Impossible]

Would these problems suggest a bad ECU ground? Does my ecu ground have to be in one particular place or can I gropund it to the chasis anywhere? A shop did my swap, I didnt do the wiring myself. Look slike pin 60 is the ground. Shoud I try just clipping this and grounding it somewhere I can see. IIRC as is it goes into a harness and Im not sure where it comes out or where it is grounded.

[Cpt_Impossible]

http://www.240sxforums.com/for...ntrol

On this it looks like pin 50 and 60 are both control unit grounds.

[Cpt_Impossible]

So I did some more testing and heres what I found:

The 10amp unfused on my ammeter does work, I just need to switch the port the probe is hooked to...

With the engine control fuse off using the ammeter to jump the terminals. It reads .46amps. On the battery terminla when I jump it it reads .50 with the fuse in, .05 with it out. So that fuse is obviously my problem area. I disconnected the ECU harness from the ECU but left the two relays behind the ecu connected. The high draw was still there. After multiple tests I found that even though the relays are identical physically, plugging them in different order changes things. I marked one plug "1" and the other "2". I marked one realy "A" and the other "B". Leaving either 1 or 2 unplugged stopped the drain. 1-a and 2-b yielded drain. 1-b and 2-a yielded a stopage of drain.

So I tried 1-b, 2-a and replugged in the ECU to the harness. The drain came back... I tried switching in 2 more relays from other areas of the car marked as the same relay and any combination of the four relays yielded a drain when the ECU was plugged in to the harness so long as both plugs were in a relay.

My next step is to make jumper cables and just connect the ECU power pin and the two Control ground pins to the ECU and see If I still get a drain and go from there but its too late and I have to work early.

[Cpt_Impossible]

anyone?