No Start on BEW Glow plug code and p0727 pending

So my car has had an intermittent glow plug code p0671 (cyl 1) for the whole time i owned the car. But a bad connection has never prevented any of my diesels from starting in 80 degree weather.
When i tried to start it today, i cranks but will not start.
the glow plug light is flashing at me while i try to start it. not sure if thats normal.
But whats throwing me off is when i scanned the codes there is a p0727 code pending. (Engine Speed Input Circuit No Signal)
Is this just from cranking it so much?
I also tried to crank it in neutral (its a 5 speed auto).
I dont want to go throwing the money at the harness just yet.
Actually what has prevented me from installing a new one is that Id have to wire it in. And i know the plugs have a tolerance of differentiation of .2 ohms or something like that. Im afraid the solder or connector will mess it up.
Should i be worried about the p0727 code?
.
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.Also ive never had any starting issues with this car. avtually the fastest starting tdi ive driven. 1 or 2 cranks every time.
its turning over so freely i thought it wasnt getting fuel.

I scanned the codes again and the p0727 code was actually stored.
I wiped the codes and tried starting again and still nothing.
Re scanned and the only code stored was the p0727.

I check the crankshaft positioning sensor and it looks good.

Also checked to make sure the rail is getting fuel and it is.

So i just realized i was inspecting the cam sensor.

I checked the wiring to the crank sensor and it looks good on the sensor side of the connector. But on 2 of the 3 wires going into the computer side of the connector the insulation of the wire has worn a little and i can actually see the wire.

I tried positioning it differently but it did not change anything.

I was thinking maybe i can put a drop of solder on them to see if it will complete any bad connection.
The exposed wire is so close to the connector i would just have to get another one.

I do actually have a donor car that i can steal some parts from coincidentally. I guess will try to swap just the sensor first. Then get into the plug.

Still. if anybody thinks the crank sensor code is a fluke from cranking. then let me know before i start tearing in.

Thanks

Ok. so i sprayed a little brake cleaner in the intake and tried to start it.
Took a couple cranks and started right up. Hickuped a little at first but once the fuel burned off it idled great.

Ran the codes. still just the p0727 code so i wiped it.

Turned off the engine. and it started right up again. did it about three times then drove around the block.

until about 2000 rpm it feels normal. But after that there is a significant loss of power. Let it set for 10 min or so and it took about 10 cranks to start which is not normal for this car.

Still no codes.

I have read that the car might run with a bad crank sensor as long as the cam sensor is working.
But i also read the opposite.

Feel like it might be something else.

The timing belt is still tight. and it doesnt feel or look like the cam gear slipped at all.

Any help would be noice.

I would say measure the resistance on both sensors and see if they are the same.
If you have the repair manual it should have the resistance range they should be.
Were you doing anything on the car that might have moved wires?
You might have to open the wire harness to check.
Last, possibly a bad ground in the circuit.
I don't know how or if that sensor grounds to goes back to the ECU.
There's a dozen things that can cause the glow plug light to blink including the brake light switch and if both back lower brake lights are out.

Installed new glow plug harness and it still wont start.

The thing that gets me is it has no sign of starting. and it throws the speed sensor code (only when i crank it for 10 20 seconds or so).

No matter what i do with the connectors nothing changes.

However i spray just a little brake cleaner in the intake and it starts right up and runs fine.
After the initial start it will start right up after that.

After i get it to start with the brake cleaner it does not throw any codes or show any signs of running improperly.

Also the tachometer is working. So i imagine that means the speed sensor is working and the timing is not running to the cam sensor.

Note: the tach speedo and all the gauges take about 5-10 seconds to register when i start it. But that has been normal with this car.

Hopefully someone can help. Im pretty stumped right now.

Stop spraying stuff into the intake. You WILL blow up the engine when the red hot glow plugs cause pre-detonation.

The crank sensor is possibly bad and causing the code. A no signal code should be easy to track down. Sensor should have 5V, ground, and 12V going to it and outputs a 5V PWM signal to the ECU(IIRC). If the signal is bad, the engine will register RPMs but have no idea when to fire the injectors.

The BEW will absolutely not run without a crank sensor signal. The BRM will, that is where the confusion sets in.

Stop spraying stufff into the intake. You said you have a donor car, swap the sensor if it's a BEW. Even if it's not the sensors may be the same. Go to idparts and check the ALH vs BEW sensor numbers to find out.

Tdijarhead said:

Stop spraying stufff into the intake. You said you have a donor car, swap the sensor if it's a BEW. Even if it's not the sensors may be the same. Go to idparts and check the ALH vs BEW sensor numbers to find out.

Click to expand...

turbocharged798 said:

Stop spraying stuff into the intake. You WILL blow up the engine when the red hot glow plugs cause pre-detonation.
.

Click to expand...

I know I know. But its just s squirt.

I am trying to find a socket to fit the bolt on the sensor. I guess its an external triple square. Rode the ol bicycle up to auto zone but they dont have a damn thing.

In the mean time i tested the one on my car.
Ill go test the one on the doner later.

I dont know exactly what i am testing as i do not have anything to go off of. So i will be as descriptive as possible.

on the plug there is 1 2 3
1-brown
2-white
3-black

Not sure what is ground but i would guess black.

I tested the voltage and resistance.

Voltage on the plug coming from the ecu unplugged from the sensor:
With the ground of the multimeter on the ground to the batt
1- 2.5v
2- 2.5v
3- 0v

with the positive of the miltimeter to the positive on the batt.
1- 9.94v
2- 9.94v
3- 12.5v

Resistance on the sensor:

The only thing that registered was between 1 and 2 and it read 1.235.

This was done with the sensor still installed and unplugged.

So i tested the sensor on the donor car. All the values are the same (that i know how to test).

Im not sure how to test a pulse signal.

But all was the same except the resistance between 1 and 2 .
On the donor it was .498. I swear i read somewhere that it was supposed to be between .2 and 1.0 and mine is at 1.2. (could be wrong)

Not sure if that resistance would fluctuate depending on where the crank is sitting. But this could be a sign that it actually is the sensor.

Unfortunately i still dont know where to find a triple square socket around me. But i need to get it done asap.

Where are you located?
I may know where to find one.

flee said:

Where are you located?
I may know where to find one.

Click to expand...

Thanks but i found one that worked. Just a 9mm with the 12 points instead of the hex.

It was weird. I got so excited that i found something that would work i just pulled it off without trying to start. ( it ran all day yesterday after i used starter fluid).
So i put it right back in and the car started up.
It was a little dirty with little metal shavings so i cleaned it and put it back in.
Now it wouldnt start. So i checked the resistance and got OL on all pins instead of the 1.2 ohms i got when i checked yesterday.
This must be the problem.

Got the one off the doner and realized that the one on my car was aftermarket. The magnet on the end was different.
Once i reinstalled the "new" one, the car started right up.
Must have just got it going enough to set the timing to the cam and would start again after that.

The confusing thing is that the code said no signal to the speed sensor. But the car would not run at all with no signal to the speed sensor.

Anyways thanks ME for MY help lol.
I know i was talking to myself but i like to log my progress to hopefully help someone and make a contribution to this amazing forum.

Honestly most of the information i could find that actually helped was from other forums this time .
Lets get it together people.

Folks on some of the other forums (vortex) may use more parts from ebay and amazon, creating this very condition. Sounds like yours was replaced some time in the past, probably the old one was still fine. Those things are as simple as they can be, shouldn't ever fail unless something disturbs the wires or the metal chuck on the end of the crankshaft.
Codes can be confusing because they only hint at the problem, the ODBII monitoring is not comprehensive.
Nice work getting it fixed!

Bad crank(hall) sensors can often be very intermittent and have very odd failures. I have heard of cases where gassers have a crank sensor that goes wild, tells the ecu to fire the coil packs and injectors at extreme speeds causing all the coil packs and injectors to fry.