no power to +b at ecu

[Cale]

hello!
i have rebuilt my engine and its in the car and i have installed the maft pro and lc-1 and some gauges.. the gauges i soldered to the cigg power and they work fine. now the problem is that i have power and ground to ecu when i put the cable to the black/yellow batt cable and brown ground to ecu... but nothing on the +b & +b1 :icon_evil
is there anyone here that can help me out and maybe where i should start looking for the problem?
Thanks!

 

[thevork]

Maybe pointing out the obvious but did you check all the fuses, including the ones under the hood?
Fuses tend to die when you start soldering without the battery unhooked.

 

[Cale]

No the fuses are fine and the battery was unhooked when i soldered...
i checked the wiring in tsrm and saw this circuit opening relay... could it be some problem there maybe??

 

[jetjock]

The COR isn't involved (it's job is a fuel pump interlock) but the main relay needs to be closed. For that to happen there must be power on IGSW. That begins at the 30 amp fusible link, goes through IGN 2 of the ignition switch, then through the 7.5 amp IGN fuse. In response to that input the ECU will output +12 on M-Rel. In turn the main relay will pass power to +B and +B1. The power side of the circuit must also be working. That means the EFI fuse and again, the 30 amp fusible must be good.

 

[Cale]

ok i see... ive checked the fuses one more time and they look just fine... and also ive checked all connections and so on but nothing. When i turn the key to "on" i can hear a relay click 2 times, but dono what relay it is?
damn i hate this..
i will try again and follow the power like you described it works and see if i find something wrong...
one more thing is that i have done the 12v fulepump mod... could that be the reason??

The COR isn't involved (it's job is a fuel pump interlock) but the main relay needs to be closed. For that to happen there must be power on IGSW. That begins at the 30 amp fusible link, goes through IGN 2 of the ignition switch, then through the 7.5 amp IGN fuse. In response to that input the ECU will output +12 on M-Rel. In turn the main relay will pass power to +B and +B1. The power side of the circuit must also be working. That means the EFI fuse and again, the 30 amp fusible must be good.

 

[Dan_Gyoba]

1. Check to see if you grounded out something. I do this my checking continuity from the terminal to ground. The +b terminal should NEVER read continutity to ground.

2. Re-check your gauges. Coincidences are rare, and if you changed something in the electrical, that's more likely the culprit than anything else. Where do you ground your gauges?

3. A bit off topic, but I don't think that cigarette power is a good place to popwer gauges from. It's not a bad location, since the gauge will be on when the car is on, but I think that it should really be ignition power, and not acc power that brings gauges on-line. Acc power is off (for example) when the engine is cranking, and there are times when gauge readings are useful while the engine cranks.

4. It occurs to me too... What gauges did you install, and where are the signal leads going to? Did you solder into any ECU leads to connect the new gauges? Might you have inadvertently cut/disconnected a wire somewhere while running your wire harness?

 

[Cale]

The gauges are grunded to the cigg ground also and yes i notoced that they only stays on when on acc... have to change that! (at first they also came on when key on but not now :icon_conf)
it is boost gauge and oil temp and then the lc-1 gauge.
and the power is taken from cig to all 3 gauges. could that be the problem maybe? also the fuse blew to the right taillight once.. weird..
i will try to disconnect the gauges fron the cig and see if that change anything...
thanks for help and please give me more clues of what could be the problem!

1. Check to see if you grounded out something. I do this my checking continuity from the terminal to ground. The +b terminal should NEVER read continutity to ground.

2. Re-check your gauges. Coincidences are rare, and if you changed something in the electrical, that's more likely the culprit than anything else. Where do you ground your gauges?

3. A bit off topic, but I don't think that cigarette power is a good place to popwer gauges from. It's not a bad location, since the gauge will be on when the car is on, but I think that it should really be ignition power, and not acc power that brings gauges on-line. Acc power is off (for example) when the engine is cranking, and there are times when gauge readings are useful while the engine cranks.

4. It occurs to me too... What gauges did you install, and where are the signal leads going to? Did you solder into any ECU leads to connect the new gauges? Might you have inadvertently cut/disconnected a wire somewhere while running your wire harness?

 

[Cale]

ok ive been out in the garage and i picked out the 30amp efi fuse and the relay clicked and the i put the same fuse back again.. and now its working just fine, the maft powered up yeeehaaa!!!
maybe the fuse where just a little bit loose!?
thanks alot again for your help yure the masters!

 

[Dan_Gyoba]

Good t'hear that it's working for you.

 

[Cale]

Good t'hear that it's working for you.

yea so far... but now the car doesnt start.. just for a few seconds :icon_evil