[rosullivan04]

Hello all! I have an '08 335i heavily modified with the DocRace kit. I blew the engine ~2yrs ago and due to medical issues I haven't been able to put it back together until a month or so ago. It has a new engine installed and everything is hooked back up. I went to start the ignition to prime the water pump the other day and found the ignition does not function when I press the Start button. The lights on the passenger side light up but not the driver side; strangely enough the lights are on all the time until I unhook the battery. If I flash the high beams all the lights fire up including the rear brake lights and the HID lights. When I press the Start button nothing happens; no key lock, no steering lock etc. The brake lights appear unresponsive as well. It's a manual so this is with the car in neutral with the clutch not pressed.

I attempted to pull codes from the DME and there's no error codes present; at least the DME is responding!. The battery was on a battery tender the entire time and all the lights appear to be bright. However, I haven't tested the voltage. The key I charged off and on with my toothbrush charger, it locks, unlocks and pops the trunk open so I don't believe it's lost its sync with the DME. I have another spare key and it does the same behaviour.

I've went through and checked all the grounding straps, positive terminals on the alternator and solenoid etc. and all looks well. I also unhooked the battery monitor to the DME in case that was broken. iDrive and dummy lights do not light up; the only light that comes up is the monochrome display with the yellow headlight warning. I'm grasping at straws here but am running out of ideas. Has anyone seen something similar to this before?

[rosullivan04]

Anyone have thoughts on this?

[nissubaru]

You don't have a multimeter? You really should. They cost $10-20 and it will tell you a lot.

I had a similar issue recently, couldn't start my car whatsoever. Just replaced the engine as well and noticed the issue when I went to bleed the coolant and prime the oil pump lol Everything appeared normal, all my grounds were tight and I had a brand new ground strap up front etc. But what I didn't realize was no good was the actual negative terminal at the battery. From the top it looked perfectly fine but when I flipped the terminal over it was kinda green and corroded. I never thought that would happen for a cable in a nice clean trunk, but it did.

If you have a multimeter you can easily test this by checking the voltages at different points on the car. For me, the negative cable when connected to the battery was only receive ~5.14V, the corrosion was essentially causing a really weak connection. I wire wheeled it off and cleaned up the terminal a bit and I then got 12.6V like I should. Ideally you would check this and then also check the voltage up front, it should be the same.

The reason my car wasn't starting is because everything was only receiving 5V of power. Some things like the radio and lights worked etc but the starter was way underpowered.

[rosullivan04]

I do, I'll have to give it a test. I assumed the ballast for the headlights wouldn't start but that might explain why the driver side isn't firing up.

[rosullivan04]

I'm getting around 12.6V coming off the battery like I should but the dash and iDrive still won't fire up when I put in the key. All the lights are firing up now, however!

[dpaul]

Originally Posted by rosullivan04

I'm getting around 12.6V coming off the battery like I should but the dash and iDrive still won't fire up when I put in the key. All the lights are firing up now, however!

Did you read that voltage at the battery? If so, try reading it at the charging point under the hood and the positive terminal to the DME under the hood

[rosullivan04]

I'm outside working on it now, confirmed I have 13.3v at all contact points. Oddly enough, my water pump just randomly turned on when I put in my key. Still no dash/iDrive, mirrors/windows. The amber light I had on the dash asssumedly for not having all my lights plugged in has now disappeared as well. I have ISTA+ installed on my laptop and am trying to see if it gives me any additional information. My Android tablet with MHD didn't give me any error codes from the DME.

Update: Just managed to get a code from the DME, 2ACB.

[cgbimmer]

just for ha ha take a jumper cable negative only put on front neg and then other side anywhere good on motor and try starting .
that's how I figured my ground strap was bad after taking out I realized I could rip cable in half brittle..

[rosullivan04]

That was a good thought! I just walked all my grounding points around with a negative terminal just in case I missed one. Unfortunately the DME is still being stubborn. What's really odd is that I can pull codes with MHD and even clear codes though my laptop when plugged doesn't light up my ODBII light or allow me to pull codes. I've went through the install a few times, about to try it on another computer.

I feel like I've made progress at least, all my lights come on, I no longer have the amber error on my dash 'though dash and iDrive are always blank', and my water pump randomly starts up when I put my key in. No matter if I put in my key or reinsert it the ignition never fires up, and my dash/iDrive etc. never comes on.

I'm hoping my ISTA+ install is bad and that there's some sort of a reset I have to perform on my DME b/c it was unplugged for over 2 years :/

[JuniorB]

All your interior functions run off the body control module, first thing to check is all fuses. If you have power to the inside, then check fuses. The other possibility is, how was the car stored? There can be corrosion behind the fuses panels, in modules, and at grounds. I’m more familiar with e60, but, these are all possibilities and just a guesstimate, and the obvious. You need ignition power first, to proceed further.

[rosullivan04]

I did check all the fuses a few hours ago and they were good. I tried another key I have as well in case it was some sort of DME security lockout; I even left each key in the ignition 24hrs. It's been stored in an insulated garage with no weather or anything like that. The line feeding the fuse block was suggested online so I checked that to make sure it was connected.

[rosullivan04]

I've got more information after replacing the DME, JBE, and having the footwell module and CAS verified as good by a DME coder. I also bought a new battery for good measure. I get interior lights and if I flip the highbeams on the lights turn on however no dash activity and iDrive never turns on, no A/C etc. Basically nothing happens when I press start. With the new DME I was able to pull codes, these sound like there's still communication issues. I've got a new fuse block I'm going to install this morning and I'll check the positive cable while I'm in there. I did go through and confirm that all the earth cables are good.

[rosullivan04]

I just went through and replaced the fuse box 'in case the positive terminal was shorting' and installed all new fuses and relays, along with checking all the cabling that i can think of under the hood. I also put my old JBE in place since it's coded to my car. I'm still in the same place I've been, other than I can at least pull codes :/ I've replaced:
Battery; DME; Footwell Module (Verified good by coder); fusebox; CAS (verified good by coder); swapped JBE (running on old one currently); replaced all uses with fusebox and relays and battery. Anyone have some ideas they want to toss out?

[JuniorB]

Since I’m doing a n54 swap, and changing everything out, I’ll touch on everything I’d do. It looks like the body control mod isn’t powering out, this controls just about everything in the car. On the e60, terminal 15 need to have power, it’s the wake up signal. Check for power coming in from the battery to the under dash fuse panel, depending how you pulled the engine harness. Did you disconnect the plugs at the ecu, at each sensor, and is it the same one? The yellow and black twisted wires and can high and low, these go to everything in the car, connector x60001 1 is low, 14 is high. This connects the speedo, I drive, light module, Bluetooth module, abs, Cas, hvac,. There is also what’s called a micro module, small white box, there’s one in the trunk, and one under the console, I’m not sure about e90, but I have them, they will corroded inside. The one in the trunk runs the body control module. I’ll look some more, need to know how you disconnected the engine harness.

[rosullivan04]

I left the harness on the DME, just disconnected the sensors and pushed the harness to the side when I removed the engine. I’ll see if the fuse panel is getting power, already replaced the JBE (Bod Cont Mod) to see if mine was bad. I feel like I might have a short somewhere or missed a positive wire so I’ll trace through my wires again. Thank you!

[JuniorB]

Ok, so you shouldn’t of lost communication if it was all pulled at the sensors. Sounds like there’s is power missing. If your remote opens and locks the doors, that’s the jbe. From my understanding, this doesn’t need coding or syncing like ecu,cas, and ignition. Double check all wires from alternator, starter, and ecu box. Make sure all power wires are on the battery, and check all fuses by pulling each and every one out to physical see if it’s burnt. Make sure your getting power from rear to front. I’d double check all these first, see if anything was missed

[rosullivan04]

Unfortunately I'm still dealing with this :/ I believe it might be down to this singular wire that's not connected, disrupting the CAN circuit. This is coming off the passenger side headlight wiring loom. I have the horn connected 'this wire is much longer than that one, but looks similar'. It is long enough to nearly reach on the top end towards the middle of the car. Does anyone know what this wire might go to? I've been looking at wiring diagrammes but haven't been able to track it down.

[nissubaru]

Originally Posted by rosullivan04

Unfortunately I'm still dealing with this :/ I believe it might be down to this singular wire that's not connected, disrupting the CAN circuit. This is coming off the passenger side headlight wiring loom. I have the horn connected 'this wire is much longer than that one, but looks similar'. It is long enough to nearly reach on the top end towards the middle of the car. Does anyone know what this wire might go to? I've been looking at wiring diagrammes but haven't been able to track it down.

Airbag sensor maybe? I wasn't quite sure what it was for when I was in there but if I'm understanding you correctly that wire runs between the reinforcement bar and the grill.

Start watching this video at the timestamp within my link (15:45), I think he pulls the same plug out at 16:10

[rosullivan04]

Holy crap, I think that's it!!! When I get home this afternoon I'll take a look and see if that's the one I'm missing. Thank you VERY much!

[nissubaru]

Originally Posted by rosullivan04

Holy crap, I think that's it!!! When I get home this afternoon I'll take a look and see if that's the one I'm missing. Thank you VERY much!

Haha no problem. I was a bit confused with all the wiring down there as well. It was some of the first things I took apart and the last stuff I put back together so I had to rewatch that portion of the video multiple times.

[rosullivan04]

Well I'll count this as a win, this is progress! After I cleared my codes my JBE registers as green! Still no dash or iDrive but I'm down from 19 codes to 14! I'm going to swap to my old JBE and see if it behaves itself.

[rosullivan04]

I just replaced the battery fuse box and I'm down to 13... this is with the IBS disconnected. Still no dashboard or iDrive, anyone have any ideas? It seems like I'm really close and that it's just power not getting somewhere. If I swap JBEs it stays the same. This is after swapping fuse boxes as well.