D5G LGP Low Voltage

[snowpl0w]

RKG01630 SN
Before buying the dozer, I tested the battery and the alternator, both tested good. Today when I ran it on my property, the voltage warning light came on and never turned off. Once I got back to my shop I got my multimeter and checked the battery output, it read 12.05 volts. I know the alternator is not putting out power, does anyone have a copy of the test procedure to verify that the alternator may be the issue? Any diagnostic pointers would also be greatly appreciated- I don’t like throwing parts at a problem without properly testing.

Thanks!

 

[Simon C]

Well it sounds like the alternator died, a battery is gone all of a sudden or you have some connection problems. Is the belt still on and tight enough to turn the alternator, have you checked all the connectors at the battery and the frame to battery griound. Have you checked all the fuses and the alternator breaker which I believe it has.
I am guessing it is a 12 volt system, maybe post a picture of your battery box and maybe can share a few thoughts. Don't think I have a schematic for it but will check and respond back one way or another.
Simon C

 

[Simon C]

Don't have the schematic, maybe Nige or one of a few other guys will supply it to help you out. If they are not around I could give you a few simple tests. By the way how many hours on the unit, how many batteries, and any previous history we should know about.
Simon C

 

[snowpl0w]

Don't have the schematic, maybe Nige or one of a few other guys will supply it to help you out. If they are not around I could give you a few simple tests. By the way how many hours on the unit, how many batteries, and any previous history we should know about.
Simon C

I bought the dozer from the company I work for. They have owned it since new, I pulled the maintenance records before purchasing and it’s been a very reliable dozer for them. It’s got about 9500 hours on it, but has been maintained the whole time since it was working daily up until the time I bought it.

It looks to have 1 12v battery, but that’s just from the limited testing I did today. I will verify tomorrow and get additional pictures. Both belts are on and tight, and the alternator spins freely when the engine is running. I can remove the side cover tomorrow and verify the belts are within spec also. I’ll also check the fuses as well, if I find a smoking gun I’ll update the thread

Feel free to let me know if there’s any other tests to try. I can always pull the alternator and have it tested at a local shop if I don’t find anything else.

I’ve been planning to buy an old printed service manual, looks like it may be finally time to invest in one.

 

[Nige]

I’ve been planning to buy an old printed service manual, looks like it may be finally time to invest in one.

Post a machine Serial Number to identify the appropriate manual.

 

[Simon C]

Not sure if your alternator has what they call a dummy cap. It is a square looking nut that is a non-conductor and is often painted yellow and holds the output cable connector to the stud. When testing from the alternator always stab the ringlet connector or apply your alligator clips to it and not the nut if it is a dummy nut.
There is usually the alternator breaker fairly close to the alternator on a panel of some kind. it could be tripped, or not tripped and power on one side only meaning the inside is burned out.
You could have the alternator power output going back to battery Positive interrupted in between somewhere. Some units had a bullet style connector half way that would burn out with lots of hours like yours have.

Nige his serial number is RKG01630.

Simon C

 

[Nige]

Nige his serial number is RKG01630.

Search for Car Publication RENR7310, priced new at $780 just so you know. Alternatively if is available on a CD for less than $500.

 

[Simon C]

One simple fast test that I do to check the cables if I don't have long enough meter leads is to clamp a long set of needle nose vice grips very firmly to the output post of the alternators lug, I then hook up only the RED booster cable end to the vice grips as it holds on well, and hook the other end of the RED cable to the ouput terminal of your battery. If it starts to charge well you know you have an open half way between.
Simon C

 

[snowpl0w]

Thanks for the replies, I will do some more testing and see what I can figure out

 

[snowpl0w]

One simple fast test that I do to check the cables if I don't have long enough meter leads is to clamp a long set of needle nose vice grips very firmly to the output post of the alternators lug, I then hook up only the RED booster cable end to the vice grips as it holds on well, and hook the other end of the RED cable to the ouput terminal of your battery. If it starts to charge well you know you have an open half way between.
Simon C

Sorry for the delay, got tied up on some other projects over the weekend. It looks like I’ve got a 12v, 2 battery setup. I’ll attach a picture. Before cranking the machine, I reach 12.26 volts on the outside battery. After cranking it and testing on the stud coming out of the BAT post on the alternator, I only got a reading of 11.5-12v. The reading was very sporadic, so I decided to get the belt as tight as possible. As my luck goes, the bolt that attaches the top of the alternator to the bracket sheared off. I’ve got to remove it anyway so I’m thinking about taking it to an alternator shop to have it tested while it’s off the machine. Will update once I get it tested and reinstalled

 

[CM1995]

I would have the alternator tested since you already have it off.

G series dozers like 14.4 volts across the system to operate all nice and happy. Since you were only getting 12 or so volts did the tractor do anything weird other than throw the low voltage code?

We've had our D5G XL slam to a stop while fine grading a Zaxbys parking lot - threw everything towards the windshield including the operator. Can't remember if it was a bad battery or an alternator - that time.

 

[snowpl0w]

I would have the alternator tested since you already have it off.

G series dozers like 14.4 volts across the system to operate all nice and happy. Since you were only getting 12 or so volts did the tractor do anything weird other than throw the low voltage code?

We've had our D5G XL slam to a stop while fine grading a Zaxbys parking lot - threw everything towards the windshield including the operator. Can't remember if it was a bad battery or an alternator - that time.

The only warning sign it has shown is the low voltage warning. Other than that it’s ran perfectly fine, granted I’ve only put a couple hours on it since the voltage issues popped up. The cat dealer can’t test it unless it’s on the machine, so I’m gonna take it to a small alternator shop and see what they say

 

[Simon C]

Sorry for the delay, got tied up on some other projects over the weekend. It looks like I’ve got a 12v, 2 battery setup. I’ll attach a picture. Before cranking the machine, I reach 12.26 volts on the outside battery. After cranking it and testing on the stud coming out of the BAT post on the alternator, I only got a reading of 11.5-12v. The reading was very sporadic, so I decided to get the belt as tight as possible. As my luck goes, the bolt that attaches the top of the alternator to the bracket sheared off. I’ve got to remove it anyway so I’m thinking about taking it to an alternator shop to have it tested while it’s off the machine. Will update once I get it tested and reinstalled

Just looking at the picture you supplied and can't really see how much corrosion there is around the battery posts. Just cause there is covers on don't mean it doesn't have white or green corrosion in between. Maybe it is perfectly clean. Maybe post a picture. And yes if you have it off get it tested, although I prefer to test it myself to check all the harnesses on the machine.
Simon C

 

[snowpl0w]

Well, time for the conclusion to the saga… my worst fear came true- the alternator is shot. CAT doesn’t have a rebuild kit and a reman alternator is no longer available. So I get to buy a new alternator. If anyone ever has an issue with the low voltage light staying on, verify the tension on the alternator belt. If it’s tight and the alternator still reads an erratic and low voltage- you’ve probably got a bad alternator. It’s easy to remove and take to an alternator shop to verify.

 

[CM1995]

Check aftermarket.

We are able to buy alternators from O'Reilly for our 279D's for a fraction of the cost of OEM from Cat.

 

[Nige]

Check aftermarket.

We are able to buy alternators from O'Reilly for our 279D's for a fraction of the cost of OEM from Cat.

By your machine Serial Number the alternator comes up as a 203-5492 and it lists repair parts - see the attachment.
It also lists a Reman Number as 10R9098.
Now that information may not be the latest from Cat but it might help you to search for aftermarket parts if you have the OEM Part Numbers to use as a reference.

 

[CM1995]

By your machine Serial Number the alternator comes up as a 203-5492 and it lists repair parts - see the attachment.
It also lists a Reman Number as 10R9098.
Now that information may not be the latest from Cat but it might help you to search for aftermarket parts if you have the OEM Part Numbers to use as a reference.

Thompson shows one available FWIW.