BMW 318i boot locked can’t get into

[ArunNewmark]

Hi, my BMW has no power at all going to it. The boot is locked with about £500 worth of tools and stuff in but the other doors are unlocked. I recently replaced ecu and when I did that the car started once and then stopped starting so I tried jump starting it and no luck and then I tested the battery it was on 8Volts. I shut the boot and it locked and then all the other doors diddnt. I thought it could’ve been the new ecu I put in so I put the old one back but it diddnt seem to make a difference. I can’t access the battery as it’s in the boot and I can’t get into the boot through the back seats or unlock it manually with a key. I don’t know what to do.

[Ossie D]

Can you charge the battery or use a jump box by connecting to the positive and negative terminals under the hood on the right side? Also check for a valet switch in the glove box.

[Greydog]

Morning Arun

Welcome to the Forum

As Ossie has pointed out you can open the bonnet and access the Charging points under the bonnet that should allow power to the boot. You should never charge a BMW direct to the Battery terminals (unless it is disconnected as damage can occur due to voltage surge.

However I think your issue may be deeper than just a dead battery. You say you changed the ECU ? when you did, did you also change or re-program the EWS to recognise the new ECU ? If not the EWS has probably activated the immobiliser. If you did register the ECU to your chassis and match it to the EWS then reregister the keys with luck it is just the dead battery

Dave

[Greydog]

Sorry Ossie

Welcome to the Forum

Dave

[DDONNY]

A couple days I decided to replace the 2 airbag crash sensors on my '92 BMW E36. I assumed that a couple of used, but cleaner, 2 sensors, would be better than the old ones with black tar coming out. My '92 engine is the best ever, five speed, and I have been doing most of my maintenance. After a short trip, 5 miles, in the dark. First came the instrument panel go dead except for the mileage numbers. It seemed to be OK but I locked the doors. In the morning, the key wouldn't open any door except for the trunk lid. I thought it was a bad battery and I put a charged one in. That didn't help. I didn't consider the fact that the one or two of the crash sensors might have come from an E36 wrecked car. Do I cut away a big hole in the hood, above the locking cable? Should I put the old ones back in? I have no way to open the doors. I think that is a rotten deal, to cause all this trouble for the owner. Any ideas? The crash sensor is next to the right/left front strut towers.

[DDONNY]

This is my only '92 photo that is already in my home computer. I have another '92 also, I'm afraid that it will do the same if I drive it. I have 6 other cars: An '87 BMW 528E, '95 BMW 325i., '96 328ic. The other 3 are EU. 

[X5smw]

Take the front grilles out and you can access the cables for the hood/ bonnet release. 
I had to do this on the x5 recently. 
 

[DDONNY]

OK. Good. Some plastic will crack but that's better than using a hole saw going through the hood. Thanks.

[DDONNY]

It looks like I will remove the full plastic bumper. That way I can reach the cable easier. I have started. Little by little. Too many errands taking up time.

[DDONNY]

Greydog and X5smw. Once I open the hood, what next? I know this time that I need to remove the battery cable. Can I just remove the airbag crash sensors and replace with the original ones (with tar coming out of the ACS). I would want to remove all of the sensors and air bags. Would that help or not? I just want to be able to open the doors with a key again.

[Greydog]

Not sure what you have done or are asking here Donald 

First the Boot/Trunk can be opened manually using the Master Key. The Battery is in the Trunk/Boot so Neg terminal off first. If you realeased the Red Lead under the Hood/Bonnet you only isolated part of the cars electrical system? (This is also the Charging Point so if charging the battery this is where to connect)

Sensors, before changing them make sure they actually need changing test them (Google for parameters) also check whether they need coding to the car to ensure they are going to work correctly. Check all fuses are intact if all OK then a Diagnostic scan should show where the Issues are

Dave

[DDONNY]

Things went well, once I used a coat hanger to open the driver's side door in the back. Also, I had bought a trunk lid some time ago (and steering wheel, driver's side door, and several other things) from a guy that was selling parts. It was lucky I got the trunk electrical part that opens up all the doors with a key. That happened a day or two later; not right away. I guess that feature had to come back to life. I'm in the process of cutting out the A/C condenser aluminum that will give the radiator better cooling. I will put in another fan motor, because the other one had seized up. I may have to put in another alternator, just to be sure. As for the airbags, for both BMW '92s. I reused the original crash sensors instead of the clean ones that were likely from a collision. Live and learn.

[DDONNY]

Update: I checked my battery and it charged in 5 minutes, so I don't have to find another alternator. All seems to be OK except for the plastic "L"s with a short rubber hose that bypass the HV/AC solenoid. Those get clogged after @ 150,000-190,000 miles (if distilled water wasn't used) and cause air pockets that try to burst radiators. I have a few more brass "L"s, so now I can throw the plastic ones away. I have to be careful I don't fog the windows though, without heat or cool.

[Greydog]

Errr not clear here Donald Plastic "L's" with short rubber hoses ???

Distilled water/Ionised water should only be used in an old style lead acid battery. The Rad and engine coolining system should be filled with the correct coolant mix to prevent cavitation and the danger of freezing in low temps. Coolant should be part of the cars regular maintenance and changed every 3 years or so. At that time all hoses and connectors should be inspected and changed where necessary to keep everything in tip top condition. Changing parts can cause as many problems as you may think your solving