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No Crank Bmw
Posted to Technical Tips Forum on 9/7/2017 18 Replies

2007 X3 towed in for no crank no start. Walked out to SUV and hopped in and tried to start. Yup complaint verified. No crank.

Noticed bright interior lights. Trying to crank engine only resulted in a minimal dimming of the lights. Also noticed while attempting to crank some strange sounds.

First was the very brief clunk of the solenoid engagement. Sounded like a typical BMW with low voltage during crank.

Also heard a repetitious clicking sound under dash that would last as long as the key was held in the crank position.

So I head to the rear of the truck, pull up the floor liner and expose a fairly new battery. A quick check of battery voltage shows 12.3 volts. While cranking it dropped to 11.5. Should not be low enough to disable starter but I hook up a jump pack anyhow just to be sure.

Still same symptoms , an intermittent quick clunk sound from starter solenoid and a repetitious click under the dash all the time the key is held in the crank position.

Remove lower drivers hush panel to locate clicking sound. Found that it is coming out of the ews module.

That is the immobilizer module. Find a circuit wiring diagram for the start circuit. Looks like starter solenoid control goes through the ews module.

The ignition switch provides positive voltage on the starter wire to module, and the module allows the solenoid to be powered through an internal relay if all the crank criteria is met.

Crank is allowed through the ews module if key is accepted, trans is in park or neutral, brake pedal is depressed and the battery voltage is sufficient.

Ok time to scan the module now. No relevant codes anywhere that would explain my no crank condition.

So I thought I should monitor some data at the ews module during an attempted crank.

I found that in time with the clicking sound the pids for park/neutral would switch from yes to no and the starter allowed pids would also switch from yes to no.

Since the trans range input was erratic at the ews and it is transferred to the ews from the trans module I decided to monitor the park/neutral pid in the trans controller during crank. It always said park.

Hmm I'm becoming increasingly suspicious of a failed ews module. So I check the ews module power and grounds during crank and find no faults in the voltage drops. I also checked for a constant power during crank from the ignition switch to the module and that too is ok. But the output to the starter rapidly cycles in time with the clicking sound.

Really starting to feel that with the erratic behavior of the ews module and validated power grounds and signals at the module, that the ews has passed on.

Since there are to big wires for the starter at the ews module, the input from ignition switch and output from module to the solenoid I decided to unplug the module and connect the input and output wires together and attempt a crank.

Wow to my surprise still no crank with the module out of the picture but the clicking noise was gone. I verified that during crank I now had power on the wire that powers the starter solenoid. It was good.

Now I checked the current on solenoid wire during crank and it's around 10 amps. That tells me the wire is connected to starter and able to flow current.

Now I'm convinced the starter is no good. But something tells me to voltage drop the engine ground before condemning the starter. See fig 1. Wow 8 volts not good.

So I attach jumper Cable from frame ground lug to engine. Fig 4. Now it cranks and runs! Cool! At least now I can drive it inside out of the rain. Check ground voltage drop while running fig 2.

Put truck up on the lift and check the ground. Cable rotted apart! Fig 3. Great replace Cable. Let it down, hit the key and it fired right up.

That was real close to me jumping to at least 2 incorrect conclusions. First the module then the starter. But a little perseverance paid off and at least this time I didn't make a fool of myself!

Hope this helps someone.

[Voltage Drop]

[Engine Running Voltage Drop]

[Broken Cable]


Robert Kenney
Gils Garage
Burnt Hills, New York, USA

Files Referenced:

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18 Replies Received (View Replies)


car Vehicle Data

2007 BMW X3 3.0si 3.0L No Crank

Engine3.0 L
Trans6-speed Standard
SymptomsNo Crank

car Vehicle Data

2007 BMW X3 3.0si 3.0L No Crank

Engine3.0 L
Trans6-speed Standard
SymptomsNo Crank