No start

[lynnbilodeau]

Just jump a hot wire to + side of coil from battery + for a quick test.
Bad ref sensor will not cause you to have no power to + side of coil.

[CMG]

I tried swapping main relay already but i'll jump it and see. Normally car turns over like a champ and starts instantly. Turns over great now i keep sayin i know it's gotta be something simple. I think my 7 is just jealous i've been driving my other cars more and is just being spiteful. No starts with a 745i are a constant and in the past it's always been one thing causing the issue which is cake to replace but always requires time to diagnose. Thanks again for the help guys it's always appreciated to be able to get good info quick and save me the time of searching.

[CMG]

What pins do i jump for main relay? After that i'm prolly gonna check ignition switch. What's the obc about, does the circuit go thru there?

[Hit Man X]

What pins do i jump for main relay? After that i'm prolly gonna check ignition switch. What's the obc about, does the circuit go thru there?

Center three to jump it/bypass the main relay. Red to red/blue and red/white should be the colors. Others should be a brown for ground and the green which is what closes the relay to send power from the red to the two accessories... the red/white and red/blue.

This will take the OBC internal relay out of the equation regardless, as the OBC is the green and green/red at the OBC relay (depends on OBC1 or OBC2 for location). And yes, the circuit goes through there. The green wire off the ign switch runs to it through the relay. EASY to bypass without hacking a damned thing up like the older 'fix' Just stuff your head under the dash on the driver's side to the main white wire distribution block (C302?) and find the green and green/red male and female plugs behind it. Just reverse them. It takes the OBC out of the start up sequence, just like a non OBC car. Simple! Never deal with it again.

You can 'hot wire' the car easily at the ignition switch. Just jump the green and violet to the red. The black is just the starter signal. No real point unless you do not have power to the accessories or to the green wire on the main relay, but easy enough to do anyway.



Once you jump the main relay, this will power up the Motronic and give you +12V at both sides of the coil with the key on, engine off. The Motronic grounds the fuel pump relay upon cranking, it is not supposed to run with the engine off. Safety feature. I suppose you could test this easily with a test light just put one end on the Positive side of battery and other on the ground terminal, upon cranking it should flip the light on.



Aside from that, the reference sensors should do about 1000ohm +/- 100ohm from what I recall. The AC voltage test is easy enough, expect about 3-4V cranking on the speed sensor and about 1/10th of that off the reference sensor cranking.

- - - Updated - - -

Here, this should help to visualize where to bypass the OBC stuff. Just follow the OBC harness, really damned simple.





- - - Updated - - -

Here is that connector from the ETM -

[CMG]

Jumped the main relay and she's purring like a kitten. Looks like my spare relay was bad too so just gonna get a new one. Thanks hitman i knew it was something simple.

[CMG]

- - - Updated - - -

I have tons of 5 prong relays but none of them match my oe one. All kinds of combos of 30, 85, 86 and 87. I'm assuming that means the 745i main relay is pretty specific and different from the ones used on other bmw and e23

[Hit Man X]

You need one with 87A and 87B both transmitting current. I will find you a PN here

- - - Updated - - -

Currently installed in my car is - 12.63-17.29004

Punched into Autohaus gave me these - 61361729004 and 0332019109 This shows also elsewhere - 12-63-1-710-726



My 735i had the same style 'main' relay. I would assume similar vintage E30/24/8 all use it. About $10 new, buy two and keep one for a spare.

[BoolJames]

Sooooooooooo I guess I knw what I'm trying this week since I already racked up $150 in street sweeping tickets. Wish my luck. Ima follow step by step. Hopefully mine is simply the relay too because I got new battery, new ground and terminals and still make klick noise but no power to starter..

[CMG]

I got a couple new style ones they are white. Gonna try to rig up a way to mount the fuse better than your zip tie solution haha. Hopefully post pics soon

[CMG]

[BoolJames]

Where u buy from? Feel like I may need a few ^^^

[CMG]

My local dealer, $13 each

[RedRabbit76]

Try spraying starter flyuid and seeing if it would start, it could be a lot of things, maybe clogged fuel screen, fuel rail sensor is out, I've seen those a lot at my shop.

[BoolJames]

Mine has no power to starter, it was running and shut off. mines electrical no doubt. @cmg , I'm gonna push my e46 m3 and my e23 down to sd one summer weekend . Let's link up for a photoshoot. (Canon 6D)

- - - Updated - - -

IG: @BoolJames

[BoolJames]

Not $13 but hey, last one they had

[BoolJames]

After a long day of wrenching I made a few purchases and drew a few konclusion! S/O to my ONLY Blackberry friend HitMan way out in Texas for guidance though!!!

[CMG]

I'd love to do a proper photo shoot with my whole quiver but I'd have to get more friends to drive them all to a location

Mine has no power to starter, it was running and shut off. mines electrical no doubt. @cmg , I'm gonna push my e46 m3 and my e23 down to sd one summer weekend . Let's link up for a photoshoot. (Canon 6D)

- - - Updated - - -

IG: @BoolJames

[sius072]

I have a no start head ache on a 745i e23, dme not grounding fuel pump, main relay is working and getting power, fp relay is working if u jump it, reference and speed sensors both read 946 and 941 respectively. can anyone give me some suggestions.

[Hit Man X]

I have a no start head ache on a 745i e23, dme not grounding fuel pump, main relay is working and getting power, fp relay is working if u jump it, reference and speed sensors both read 946 and 941 respectively. can anyone give me some suggestions.

Start a new thread. Either your -013 is dead or you have crank sensor not functioning, Ohm test is not the only test.

[sius072]

thanks