Main relay location

[chris59]

Hi,
I'm still playing with electrical gizmos on my 350I : test #15 ("resistance of injector circuit", Wedges Epistles, Page 22) request to find the main electrical relay, but how to identify this specific relay, and where is it located (behind the ECU, as the others ?) ?
Injector #1 seems to not working anymore, this is the last of the tests to follow before an injector swap.
Thanks for your help,
Chris

[BlueWedgy]

Sounds like you may have a break in a wire, the injectors fire all four Injectors per bank. So if 3, 5 and 7 are working and 1 is not then there may well be a wire break, or bad earth?
Check all wires at the back of the cylinder head.
Check pin 15 I think from the ECU connector to the Injector #1 plug for continuity.
May also want to also check the power resistor too.

Edited by BlueWedgy on Monday 23 March 20:21

Edited by BlueWedgy on Monday 23 March 20:21

[chris59]

Hi,
Thanks for your message BW.
I've already checked the power resistor, compare the #1 injector resitance to the others, and checked the continuity between the power resistor and the injector (Yellow/narrow green stripe if my memory is good), everything seems to be correct.
I also checked each connections and pins on the ECU side, all was fine, but hadn't checked the earth yet.
This afternoon, I made a fuel feed with a T pipe from the cold start injector hose to feed a spare injector connected to #1 injector plug, it was perfectly spraying in a small jarr.
One I get this result, I swapped the tested spare injector for the -apparently- not working one, but the problem is the same.
So, it's not the injector itself.
I'll check the continuity from the ECU connector to the Injector #1 plug, good idea.

No idea about the location of this so called "main relay" ? It seems that the resistance value of each wire is crucial in this injection system.