Hi i have a 259d with an electronic engine that it's throwing a speed engine position sensor alarm I changed the sensor and it's still does it, what should the signal look like if I hook onto it with a scope to check it at the sensor and at the ECU
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Engine position sensor alarm
- Thread starter AO299D
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- 259d alarm engine problem
Nige
Senior Member
Machine S/N and details of the Diagnostic Code should assist in getting you a troubleshooting procedure.
As a shot in the dark it's not something like 636-8 is it..?
As a shot in the dark it's not something like 636-8 is it..?
Only known good wave forms library I know would be https://www.aeswave.com.
But that’s for the cars.
Manual for your Percapillar should have those also.
But that’s for the cars.
Manual for your Percapillar should have those also.
Nige
Senior Member
See where the attached procedure gets you.
I attached the electrical schematic as well. You'll probably need it to locate the resistor on the engine harness and to trace wires. Maybe the illustration below might help. The resistor is circled in red, tie-wrapped to the harness
mg2361
Senior Member
This machine only has 500 hrs and looks like new around the engine I tested the resistor and it tests the proper resistance last night I hook my scope on to the signal wire and I found that it's skipping pulses do you think I should cut the wires and change the plug I once had to do that on another skid steer
Is the skipping random or regular? Problem might be mechanical, like improper gap or mechanical damage to a teeth.
Test the wires under load, check the sensors on the same branch of the feed, wiggle test, you know the drill.
intermittent loss of continuity, in the plug is not only possible issue, there’s more possibilities.
No, under load means load up the particular wire with something, for example I have device called LoadPro which with pressing of the button can induce the load of 400mAmp to the wire.
On something more substantial people use 55 watt headlight.
That’s more for checking loose contacts or internal wire damage, when only one or two strands are left. Or what you suspect - loose crimp or solder of the wire to the pin.
if using multimeter you check ( or induce) the voltage on (through) the wire, then after you load the wire and voltage drops substantially - it means you have an issue!
if voltage remains relatively the same - it means that integrity of this particular branch of wiring is sufficient.
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I'm not exactly sure how it can not connect but I have tested two sensors now and with not coming a steady pulse to the wire right behind the plug I think that's the only thing it could be but maybe I'm just missing something yet
like I said before - there can be more issues then bad sensor or bad plug.
It might end up being bad ECM, but you’ll have to “get there”!
Because calling it ECM is a very difficult decision, and one must exhaust all other options and possibilities before making that decision.
Check your diagram, check everything that on the same branch that can pull your signal down. It might be another sensor or wiring.
Some brands are notorious for having low quality wiring that have damage to the wires deep inside the harness.
I am not dismissing the bad plug option - simply pointing out that there more possibilities!
Nige
Senior Member
Did you try the testing procedure in Post #6 above.?
If so what was the result.?
Another suggestion. Find every major/minor harness connector between the sensor and the ECM. They will be shown on the electrical schematic. Open up each connector in turn and do the "wire pull test" on every wire in the speed sensor circuit. It won't be the first time to find a connector where the pin/socket has not been pushed in far enough to lock correctly. IMO doing the basics is what needs to be carried out before starting to get into the more esoteric stuff like putting a scope on the sensor signal.
If so what was the result.?
Another suggestion. Find every major/minor harness connector between the sensor and the ECM. They will be shown on the electrical schematic. Open up each connector in turn and do the "wire pull test" on every wire in the speed sensor circuit. It won't be the first time to find a connector where the pin/socket has not been pushed in far enough to lock correctly. IMO doing the basics is what needs to be carried out before starting to get into the more esoteric stuff like putting a scope on the sensor signal.
yes everything looked good and i checked the continuity between the ecm, resistor and sensor should i test that under load yet or would the next easiest thing to be to swap ecms with another 242? boy i hope its not the teeth on engine itself i guess i didnt check that from the procedure, would likely have to tear engine out to do that?
Nige
Senior Member
Why would you want to "diagnose" it..?
It's nothing more than an information message telling you that maximum engine RPM has been limited until the engine warms up sufficiently..........
Once the coolant temperature rises above a predetermined point the message will disappear on its own.
..........this feature also includes a warm-up period in cold start conditions. This feature limits the engine speed to certain RPMs for a short duration based on coolant temperature. This event is normal and designed to protect vital engine components. See Table 4.
It's nothing more than an information message telling you that maximum engine RPM has been limited until the engine warms up sufficiently..........
Once the coolant temperature rises above a predetermined point the message will disappear on its own.
..........this feature also includes a warm-up period in cold start conditions. This feature limits the engine speed to certain RPMs for a short duration based on coolant temperature. This event is normal and designed to protect vital engine components. See Table 4.
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