Power windows/Electrical Issue

[darkodin6926]

Hey guys Andrew here i am new to this forum. I've been building for the last 6 months my 1987 2 door 325is with an 04 gto ls1 motor, So the issue at hand is my power windows/sun roof and heater control don't work. I put a psi conversion stand alone wire harness in for the engine, and took the stock Bmw engine harness out. I was messing around with the test light last night and touched the yellow/blk wire that comes out of the Fuse box " starter signal wire" and the heater turned on and the power windows/sun roof all worked..so i think i have a bad ground or need a ground some where. Since i took the bmw ecu and wire harness out do i need to ground something else or should it all be fine? Didn't know if someone ever had the same issue. Thanks in advance for all the input

[darkodin6926]

So i knew once i posted i would probably figure it out so looking on what the Vorshlag group posted back in 2010 on some forums having this same issue,

"The K5/K7 unloader relays disconnects some circuits during "START" to maximize voltage to the starter, So During start the Black/Yellow is switched to a positive charge, which i would assume could send positive to the k7/k5 relays, therefore de-energizing the relays.

Once started, black/yellow is back to doing nothing, so we can assume the terminal goes back to a Ground state through the starter housing"

Which explains why when i touched the black/yellow wire with the test light everything worked fine, The black/yellow wire will be grounded from the starter and then switch to power when the key is on "Cranking" position to maximize voltage to starter and then once started key back on red. the black/yellow wire will go back to be a ground. hope this helps anyone Thanks again.

[jlevie]

K5/K7 are the cause, but that explanation of how they work is wrong. Cars produced from 9/87 on have a three terminal starter as opposed to the more conventional two terminal starter. The third terminal is the unloader switch. When the starter isn't operating that switch is closed and grounds the terminal. When the starter is operating the switch opens. The relay have power applied to their coils when the ignition is on and the ground side goes to the unloader terminal. The unloader wire is pin 15 of C101.

Black/yellow wire is the solenoid control signal from the ignition switch.