[MR OHNOZ]

Hi guys, I'm trying to resurrect a project 335d. Did a bunch of work on it: new top turbo, piston rings, rod bearings, walnut blasted intakes, bunch of single use bolts replaced, new battery, and various other mods. It cranks but does not start. Throws a u0100 code. I'm thinking since it is a diesel, it should start if it were getting fuel coming out of the injectors and cranks.

So, with the u0100 sort of indicating the computer isn't getting power, I checked the fuses in the fuse box, and checked the set of fuses next to the computer and blue relay. All good. Checked the blue relay next to the computer. Click, click, the relay appears to be working. Checked the power coming into the relay with the key in accessory (fuel pump ran, lights powered on, dash powered on), no power to the relay. Checked the power on what I'm thinking was the lead that feeds the relay socket, no power.

Also checked the battery distribution box given it has a fuse-able link that can burn out. As best I can tell the distribution center seems okay. It shows continuity between the positive clamp that connects to the positive post of the battery and all the outgoing sockets? Given that one of these outgoing leads powers the computer supposedly.

Given I don't have a wiring diagram, I could be wrong about this being the lead to the relay socket and probably fuses inside the set next to the relay. So, anyone with a wiring diagram or experience is more than welcome to correct or confirm the following. I'm thinking (but could be wrong) that this lead is the one that powers the relay socket and probably fuses inside the set next to the relay. It's the medium diameter lead that attaches to the post (on the inner fender with the post shrouded by black plastic cover). This lead is between the large positive lead (one with the removable red cap) and the larger lead, that attached to another post, that goes over the back of the engine and down to the starter (also shrouded by same black plastic cover as the medium lead). It isn't the medium diameter black lead which looks to be a ground attached directly to the inner fender.

I'm thinking to chase the no power, in this maybe relay powering lead upstream. It appears to be an open between the battery distribution center and the computer powering relay. But thought I'd check with forum to see if anyone has had a similar experience. Any help would be greatly appreciated. Also though this info could be useful to anyone with similar problems.

[MR OHNOZ]

Follow up. I now have ISTA D & P. Used ISTA D and looked at the fault codes and module tree results. All green modules, except DDE red. Checked the suggested repairs. I'd already checked fuses, relays, and connections indicated by ISTA D. I'll dig further into CAN connections, and track power path to and from DDE. But before doing the CAN stuff I plan to check the continuity of the cable (one of the big ones with yellow dot on its connector) that comes out of the battery distribution box and terminates (I think) on the passenger side inner fender of the engine compartment. May be that cable has an open.

[lnxguy]

You've bled the system right? It can take a while. Crack the #1 fuel injector nut and see if you're getting fuel...

[MR OHNOZ]

Solved, maybe? 61126938504 missing. This car was a gift, and it needed a lot of work. Also, some parts had been pick off of it apparently. Was ohm-ing the wiring and cables between the battery distribution box and the terminal (the one that wasn't powering up) on the inside of the passenger fender. As per previous findings. None of the cables going into the battery distribution box ohm-ed to the dead terminal believed to be the one powering the dde. So, I pulled the battery out to look around to see if a cable had been left unattached and covered by the battery. Looked in compartment where the battery sits, and saw two red shrouded terminals sitting on the backside of the fender wall. The upper/outer most terminal had a cable attached to the cable that clamps on to the battery's positive post. Ohm-ed that circuit upstream to the starter and alternator previously. The other terminal (lower/inside) was naked. No cable attached or laying around. Ohm-ed that terminal out and it went to the circuit that powers the one that wasn't powering up. Found the missing dde powering cable pn 61126938504. It goes from the battery distribution box to the dde powering terminal. I've got one ordered. I'll post follow up after giving it a try. Hopefully this will solve the "why isn't the dde getting power" issue.

[MR OHNOZ]

Originally Posted by lnxguy

You've bled the system right? It can take a while. Crack the #1 fuel injector nut and see if you're getting fuel...

Inxguy, thank you.

Nope, I didn't bleed the system by cracking the #1 injector line. This is my first diesel, and I'm a noob on diesels. Thank you, I'll do the bleeding you suggest.

I did test for fuel delivery by opening up the leak off harness, and fuel was flowing at a steady rate. Thought that would bleed the injectors and lines. Please correct me if I thought wrong. Also, ran ISTA D on non-running but powered on engine and low pressure electric fuel pump. No injector or fuel related codes.

My prospects on getting this m57 going are looking better now that I have a handle on ISTA D indicated no power to the dde and u0100. There's a short cable between the battery distribution box and a terminal (down low in the battery compartment) that powers the dde. That short cable was missing. Short cable ordered. Fingers crossed.

[lnxguy]

These can take a while to bleed. Just keep cranking. Once you get fuel coming out of the #1 injector (At the nut, that you've loosened) you should be really close to having this thing fire up.

[MR OHNOZ]

Yep, lnxguy was right.

Cracked the retaining nut on the #1 injector, cranked the engine; no diesel came out. Then I remembered that previously (when the DDE wasn't working because it wasn't getting power) the electric fuel pump was pushing diesel through the leak off harness, and I could hear the electric fuel pump run whenever the ignition was on.

Since then (fuel pump running and not) two things have changed.

One, the missing battery positive cable (little one that feeds the cable going to the DDE) has been installed. The DDE is powering up nicely and, ISTA D shows no serious fault codes (just sunroof code, trunk latch code, junction box code).

Two, my son went through the fuses and some of them didn't match the "fuse amp vs. slot location cards" that came with the car. He installed the fuses to match the cards, thinking they were right. I did my own cards vs. fuses check and they match the cards.

Is it possible the cards' information is incorrect. I've tried finding a fuse diagram online without any luck. If anyone can point me to one I'd greatly appreciated the help.

Powered up the fuel pump from a fused battery source and it worked. So its not the pump. Looking like its power to the pump.

Tested (multi-metered fuel pump power connector (red/white wire connected to brown wire)) with the ignition on, and again with the engine cranking; no power (red/wire that powers the fuel pump motor). I'll be checking the brown ground wire that grounds fuel pump motor as that can happen based on some research.

Hoping for something with the fuses, as the pump was working before. As always thanks in advance.