main relay issues (E34 harness) - gurus check in!!!!!

[e30_kid89]

everything has been looked over and over and installed...basically ready for a start. i have a M50TU e34 harness. now X20 - C101 connection wise i have only wired up the fuel pump(green/violet), ignition(green), alternator(blue) tach (black), and both starter wires (black/yellow), (black green). there was only one ring terminal on my e34 harness that had a red wire....i put it in place where the old e30 main relay connects to the +12V post i belive that conenction is correct. on my harness there was 2 ground rings (brown), (brown/orange) and they've both been grounded. also the ground strap from the chassis to the mount arm is all fresh making a clean connection. now there problem after my relentless testing lies within the 3 relays. termainal 30 from the main relay IS getting +12V...how ever from my understanding when the key is turned to RUN, the the two 87 terminals red/white are supposed to recieve/distruibute power from terminal 30 throughout the harness. they are not. the fuel pump relay's red lead wire (terminal 30) is also getting +12V. in run there is no noise from the pump. when i jump the terminal 30 on the fuel pump relay to the green/violet lead, the pump does operate and pump fuel. on the main relay when terminals 30 and 87 are jumped, pin 54 going to the DME recieves 12 volts long with pin 26. ive tried starting the car with the mentioned jumped and still no start....how do i check if the relays are switching the ground signal to the ecu? so far i think the DME isnt initiating any fuel/spark action..have no idea why. BTW all my wiring charts where all made from scratch using the e30 91 318i. 89 e325i and 94 e34 ETM's thanks for reading,



Devon.V

[EtaSport]

If you definitely have power at the relays, and power at the computer then your ecu is bad, or there is something wrong with your harness (or ground wire). The ecu turns on power by i believe grounding the main relay and send 12 volts to the red/white wires. You need 12 volts on the red/white wires to be able to do anything.

You must have hooked everything up right to get 12 volts at the relays, so unless you have a grounding problem, i'll put money on ecu. If you have access to another car I would test yours in it to see if it would work. Thats how I ruled mine working, and was able to find my issue quickly when mine wouldnt start.

[e30_kid89]

thanks for the reply......imma try to see if i can test that ecu in a bud's e36 soon hopefully.......anybody else. jason???:p

[EtaSport]

You could check for switched power out of the ecu by back probing the red-white wires at the connector. There could be a break in the wire somewhere. Possible, but not realistic, although I have seen it before in a bmw harness.

which ecu do you have btw?

[e30_kid89]

You could check for switched power out of the ecu by back probing the red-white wires at the connector. There could be a break in the wire somewhere. Possible, but not realistic, although I have seen it before in a bmw harness.

which ecu do you have btw?

i have a 09/94 red label 413 DME.

if its no the ecu, then i beilve it may be a grouding issue.......i looked on the box and one of those .5 brown/orange wires doesnt look to good in shape, and this was before i tried anything, infact before i even hooked up the battery.

[e30_kid89]

checked all the grounds...they're all ok. also ive just wired in the check engine light to the cluster. nothing. also looking at the ecu pin out again... when the green ignition on wire sends pwr to the ecu the computer itself is supposed to control the main relay and fuel pump relay via pins 27 and 1 respectively. so right now the lack of fuel or spark points to the ecu.

[e30_kid89]

update: i tested the ecu in a e36...it starterd perfectly, so ive decided to go back and check my wiring......wiring's ok. so i did some more testing with my volt meter and things point at the main relay. on pin 56 im getting 12 volts from the green ignition wire.....i cheked all my grounds that go into the dme, they're good. AFAIK for the e34 harness, there is only ONE power wire that goes to the dist. block and 3 grounds (two on the harness, and the ground strap). they're all grounded......my problem with out a doubt lies within the main relay.....the relay doesnt click or do anything...i switched it for a working relay from my other e30, no workie switched power from the red/white wires is not getting to pin 54 on the DME amd the fuel pump relay.....ive worked backwards and eliminated all other causes so now what the hell is goin on????/

[imdarkmatter]

any update? im having the exact same issue to the T. if really like to know if you or anyone solved this.