Volvo EC290B engine speed sensor problem

[uffex]

Good day Alex
You are in safe hands with FwF.
Kind regards
Uffex

 

[funwithfuel]

If you look at the E-ECU connector, it is 2 separate connectors in a modular housing. You can disassemble it carefully. In fact, I advise to disassemble. The sharp bend right out of the connector often causes chafing. Pay close attention to orange/grey and yellow/brown twisted pairs up top. Number one cause for CAN errors.

 

[alex111]

Thank you, think I understand. Going to tackle this tomorrow and will report back here after!

 

[alex111]

Hi @funwithfuel I have performed the passive testing on the camshaft and the crank sensor, and believe I may have found something. Resistance between both pairs should be 3.9k ohm, per the passive testing paper. My results below:

Camshaft, EA7-EA18: 3.57k ohm

Crankshaft, EA30-EA31: 0.92k ohm


If I unplug the sensors I get perfect resistance on both pairs (so no crossbleed right?).

Am I right thinking this tells us the crankshaft sensor is bad?

 

[alex111]

Update: I tested with a second brand new sensor (just plugged it in and sat on top of engine). It gave me a 0.95k ohm reading (EA30-EA31). So I'm thinking this must be the normal resistance between these connectors after all, and I am misunderstanding something maybe.

If the wires ea30 and ea31 are bad somewhere I could understand why the decreased resistance, but then they would not show 100% resistance when the sensor is unplugged. Right?

 

[alex111]

Then there is the other paper you sent me which says that ea30-31 should be between 775-945 ohm when (128 sid22 paper). And this would match my sensor, but then I am not understanding where the 3.9k ohm from the passive testing paper fits with that equation.

 

[funwithfuel]

The 775 to 945 is what I would go with. Another thing you can do. Kinda hillbilly but works. Change from ohms to volts AC. Then hold the sensor near a spinning drill chuck. You should produce a weak AC voltage.

 

[alex111]

Sorry for the question spam, but looking at the active testing paper you sent me, it does not appear to have tests defined for the two sensors. Those cells are blank. It just says to refer to passive testing in the misc column. Can you advice if I am right thinking there are no applicable active tests for these sensors?

 

[alex111]

Yeah, sensors both appear to be good. And I am not seeing any signs of shorts or crossbreed on either pair.

Does this indicate my problem is mechanic, ie shedding inside the engine?

Anything else you'd check on, apart from opening the engine to look for shedding?

 

[funwithfuel]

Not necessarily mechanical yet? Someone else had recently had a similar situation. He said his harness was pinned wrong or something. I'm away from my computer right now. Did you try the drill trick?

 

[alex111]

Yeah I did on the camshaft sensor and the new crank one. I saw something tick by on the multimeter (ac volt). So I'm fairly certain those are both good? Both being new and machine does start and run, which I don't think it could without at least one of them being good right?

 

[funwithfuel]

You took the one out of the back, near the flywheel? If there was no metal fuzz, you're not shedding material off the cam. That magnet in the sensor would have grabbed it.

 

[alex111]

Yeah ive taken the camshaft/flywheel sensor of (and replaced it with a new one too). So happy to hear it was that easy to check for shedding (that went over my head before, I think you already tried telling me that), but definitely no metal fuzz on that magnet.

Any other ideas what I might want to look at? I just put the machine back together and started it up,. Same symptom unfortunately.

I did ch3ck all the other passive things the paper mentioned since I had it apart, but found nothing too alarming. The pumps were all a bit lower than paper called for but guessing that might be normal.

 

[funwithfuel]

Did you check at EA /EB connections or at CO01? Did you measure resistance values from end to end? ie from sensor to connector, each wire? Total run resistance should not exceed 1 ohm. Did you flex the harness with your meter hooked up? Especially around P-clamps and brackets? Did you disassemble and inspect the E-ECU connector for vibration induced chaffing? You're only coding for crank, so that must indicate that either the signal is corrupt, shorted, open or shorted to power or ground. Does the error log as soon as you key on, or does it wait till the engine is running? I know it's a challenge but is there any indication that a belt might have failed and bent the sensors anchorage. IIRC , it's just a piece of pot metal. Does the tone ring show any indication of impact? Is the harness pristine along the engine? Very often the tin cover that hangs over the injector side cuts into the harness. Usually causes injector codes. Just some stuff to look for.

 

[alex111]

Did you check at EA /EB connections or at CO01?

I tested at EA/EB only today. Am I right thinking I would get to CO01 up by the engine - where it connects to the fuel injector harness?

Did you measure resistance values from end to end? ie from sensor to connector, each wire?

I put my jumper cables into EA30 and EA31 at the EA/EB terminal and then I put my multimeter on them, and that's how I got the 0.92k ohm reading. Is that good, or should I have done anything else there?

Total run resistance should not exceed 1 ohm. Did you flex the harness with your meter hooked up? Especially around P-clamps and brackets? Did you disassemble and inspect the E-ECU connector for vibration induced chaffing?

These things I did not do - I will on my do-over tomorrow.
As for disassembling the E-ECU connector, I wasn't sure what this meant before, but I think you are saying take the actual connector itself apart - and this is where I will find those twisted colored wires, correct?

You're only coding for crank, so that must indicate that either the signal is corrupt, shorted, open or shorted to power or ground. Does the error log as soon as you key on, or does it wait till the engine is running?

It does not log immediately on key on, or even engine on, but it is 100% predictable. Here's the exact flow that will throw the error:
1. Turn key on.
2. Start engine (on lowest RPM setting).
3. Engine started, can sit here and as long as I like without error, and can operate any hydraulics including tracks without error.
4. Turn RPM up 2 or more clicks, and the error will happen within 2-3 seconds guaranteed.

I know it's a challenge but is there any indication that a belt might have failed and bent the sensors anchorage. IIRC , it's just a piece of pot metal. Does the tone ring show any indication of impact? Is the harness pristine along the engine? Very often the tin cover that hangs over the injector side cuts into the harness.

I can't speak for the tone ring right now because I have not tried inspecting it yet. But I can say that the anchorage, the harness (sensor wire) and the sensor itself are all pristine, zero evidence of any belt damage or similar. The old sensor that I took off was also completely intact, no visible damage.

I will try to inspect the tone ring tomorrow.

Given my description for how to trigger the error above and how the error doesn't happen if I keep tractor on lowest RPM, is that a clue for something?

Usually causes injector codes. Just some stuff to look for.

I really appreciate your help and keen insights.