E39 no crank no start help

[Smashleytulsa]

I'll start by saying that I've done a lot of research on this.and I think I have it narrowed it down but would like some others opinions. I have a no crank no start issue that is random and the car will not crank but for some reason when I get it on a trailer and haul it for an hour and get it off of the trailer it decides to start again until I drive it for a couple of days or a couple of places and then the key stops cranking the car. It's not the starter because I have tap the starter and it turns and also pulled the ews harness out and jumped pins 1 and 2 and the motor cranks but doesn't fire so that leads me to believe that the key is still good. With the ews sensor unplugged would that stop the car from trying to recognize the key and let it crank? I'm trying to figure out if this is a key issue or an ews issue before I go to the Stealership and start throwing money at them.. when the car will not start and I turn the key on I can hear the fuel pump or something that sounds exactly like a fuel pump whirring up.. with key on and passenger visor down there are no anomalies and when I hauled it to the dealership and got it off the trailer it decided to start so it's kind of hard for them to diagnose it so I'm trying to figure out if anybody has experience in knowing if this would be key or ews.. also it is a new battery

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Sorry that was really long haha talk-to-text

[JimLev]

Welcome to the forum.
So have you checked all the battery connections all the way from the battery to the starter and alternator? Battery load tested too?
With the EWS disconnected it won't start.
Do you have INPA? That will tell you a lot.

[CPHES]

If you only have the problem after the car is hot, then likely the starter is contributing.what are you tapping with? that could be making the bad connection ok for a time.

[riverdadd]

this thread was helpful when I had a similar problem.... hope it helps

Thread: EWS 3.3 101: Why your car won't start, and, why your mechanic and friends are wrong

[Smashleytulsa]

Temperature doesn't matter

[m735is]

What is the condition of the under passenger seat fuse box? I had a similar situation - one of the connections on the front of the fuse box was rusted away. I forget which fuse number but you'll know when you see it, if that's the problem.

[Smashleytulsa]

I haven't checked the one in that car but I just fixed one in my 2003 , I haven't had any other electrical problems associated to or similar to what might a car did.. but that fuse box being messed up sure can do some funny things

[TiagE39]

The under-carpet fuse box (aka Fuse Box No. 4 in the Bentley manual) m735is mentioned powers several engine starting assets, including the Engine Control Relay (F104), the EWS module (F110 there and F12 in your glove box), and the ignition switch (F114). By any chance do you have airbag light or any non-functioning interior equipment (e.g. lights, power seats, steering tilt, etc)? Those can also point to trouble with this fuse box.

[Smashleytulsa]

Nothing going on in the interior and I think it has an airbag light but I can't remember, it's at the dealership right now. I went ahead and got a key for it since it was only $80 and when I get it back I will get into the fuse box. It's random when it happens and it does throw the ews transmission parity code

[Asbradley21]

Test your ignition switch with a volt meter. Mine would start irregularly like yours and didn't present any weirdness with the passenger visor test but after testing the switch (under no start condition) with a volt meter proved the switch to have failed. New switch and it was good as new.
Make sure you test it when it won't start, as it's intermittent it will test as good when it does start.

[mattmar1]

the f4 fuse panel under the carpet is the 1st distribution point for B+ coming from the battery.

[Smashleytulsa]

If I pull the ews harness from the sensor and jump wires 1 and 2 it will crank so I don't think it's the switch

[mattmar1]

that would lead one to think that the EWS, ring antenna, or the fob transponder has a problem.
as JimLev stated in post #2, having INPA or getting your hands on it would help you a lot here. without knowing what the car's systems are doing when you install the key youre kinda whizzing in the wind.

[Smashleytulsa]

It was the key apparently.. I ordered a new key and it works but at the same time my old key that would randomly start the car doesn't start it at all now, it only cranks so I'm wondering what they did

[Chedley]

Well, you have a defective old key....throw it away.
And order a second key as a back-up.

[kaotikal]

Is there any way to figure out it the key before going out and buying a new key?

[goz777]

see if it talks to an AK-90, also check if it responds to a RF tester