Cat D5G service manual and help

[Simon C]

It certainly would be cheaper than investing in a replacement ECM which is what the OP was thinking.

Yes it is hard for a computer to run if it does not get clean power to it. Clean ground just as important.
Cheaper to test sooner than after is my moto.
Simon C

 

[epirbalex]

Have tested two different machines lately that had too much Alternator AC ripple voltage and it was causing wonky things. On one the computer was reporting voltage problem.
Very fast test to do to rule out defective diodes causing voltage and amp problems.
Multimeter on AC Volts not DC. Red test lead on output post of alternator with engine revved up and lights and fan on to create load, while putting Black test lead on Negative post of Battery. A reading over 500MV is indicative of faulty diodes in alternator on a 12 volt system. I don't have the schematic but if it is 24 volt then the number would be like 1.0 volt AC.
Worth testing and may help in diagnostics before buying Alternator.
Simon C

Can AC and DC volts or current exist in a wire at the same time ?

 

[Simon C]

Can AC and DC volts or current exist in a wire at the same time ?

Yes they can. Take any vehicle in your yard. Rev up the motor and apply as much electrical load as possible, fan , lights, seat warmers, rear defog, and check the alternator output post ( Not at the Battery Positive as the battery will act as a heat sink ) with your Red test lead and your Black test lead to the battery ground while in AC on your meter. Set meter at less than 10 volts if possible. You will find that as the load increases so will the AC voltage leakage from the diodes. It will start low and will rise to 50 or 100Millivolts AC up to maximum 500Millivolts AC. The hotter the alternator the more they seem to leak.
Then disconnect your meter leads and switch to DC and you will get about 14.4 volts from the Alternator Output terminal, to the battery negative. Test best done with motor around 1500-2000 RPM and some electrical loads on. Hope that answers your question.
Simon C

 

[epirbalex]

Yes they can. Take any vehicle in your yard. Rev up the motor and apply as much electrical load as possible, fan , lights, seat warmers, rear defog, and check the alternator output post ( Not at the Battery Positive as the battery will act as a heat sink ) with your Red test lead and your Black test lead to the battery ground while in AC on your meter. Set meter at less than 10 volts if possible. You will find that as the load increases so will the AC voltage leakage from the diodes. It will start low and will rise to 50 or 100Millivolts AC up to maximum 500Millivolts AC. The hotter the alternator the more they seem to leak.
Then disconnect your meter leads and switch to DC and you will get about 14.4 volts from the Alternator Output terminal, to the battery negative. Test best done with motor around 1500-2000 RPM and some electrical loads on. Hope that answers your question.
Simon C

It does , and thanks .

 

[Snapper]

It certainly would be cheaper than investing in a replacement ECM which is what the OP was

So we replaced the alternator, the old one was not the right output. All of that is squared away. We ran gauges on charge pumps both show 300 psi, until it acts up. Then they both drop to 230. Parking brake shows 250.

We did find that we can make this happen when pushing a large tree spinning both tracks but as soon as the blade is operated in any way in throws the parking brake light and looses pushing power. We can push all day allowing the tracks to spin down unit the blade is moved.