Good evening! I have a 07 cat 304 ccr that I’m having issues with. It has been going dead throughout the day. I thought it was the alternator bc my bracket broke a while back and I have a bandaid on it to keep it running. The belt it turning fine and not slipping. I checked the voltage and it was 15.5 at the alternator. So I started to think it was my battery. Had my battery checked and it only had 16 cranking amps left. I was thrilled that I found the problem. Well after a few days running the juice out of the new battery ran out and machine was dead. So I was back on the alternator kick. Went and bought a new alternator and a day later the machine is dead. I hook the jumper cables on it every few hours to get me by to finish this job up. I can literally watch the volts run down on my multi meter while it’s running. Once it gets down to about 8 volts I loose all functions. I check my volts at the alternator and it’s reading around 65 volts? Can this be right? What’s my next step? Also the plug connections on the back of the alternator aren’t the greatest. Would this cause it not to charge? My battery light has been on forever but kinda forgot about it bc it always starts. And advice or direction would be much appreciated. Thanks.
Is this the same machine FPK00911 that you posted about before.?
Yes it is.
This is not my area but I have the electrical schematic for the complete machine if anyone else wants to try to help you.
You say 15.5v at alternator, what about at battery? Possibly broken wire or circuit breaker between alt and bat. Does this machine have a intake heater or glow plugs? If those are stuck on will suck all the power from alt.
Have a look at these two fuses.
If I seen a copy of the schematic I could give you 5 simple tests to verify you have good cables under load, and alternator charge circuit connection strength. Do you have a quality mutimeter as the 65 volt reading in post #1 is weird and needs to be proven wrong. Simon C
The battery has around 11.8v and the alternator has around 15.5. When the alternator read 65 it was with a good quality meter. When I seen it was 65 I went back and check the battery just to make sure it was working correctly. It only read 65 at that time. It’s running between 15 and 16.5.
My alternator guy says I probably have a break or bare wire that’s running to the alternator. I am going to run a new wire in the morning and see if it takes care of it. Also it does have glow plugs and they seem to be shutting off.
I will look at the those fuses also tomorrow. I know I have issues with that fusible link sometimes.
15 and 16.5V means the alternator is being controlled by the regulator but has lost its connection with the battery. The older alternators with some load on them run at 14.2V but alot of the newer machines with calcium batterys can got to 14.6V. If you continue to run the alternator open circuit like that may burn it out even though there is no load. The internal magnetic eddie current builds up in the stator and they can catch fire. It is likely a fuseable link or wire issue and even a earth strap to the engine. A 12V alternator can produce 65V if the regulator has failed in the on state. When i was young and just for a joke I modified the wiring in an alternator and managed to get 300V out of it.
Would be a good idea to place positive meter test lead at alternator Positive output with unit running and place negative lead at center of battery positive post. What does the meter read in DC Volts . Anything over lets say 0.4 volts points to bad connection through to battery. As 007 says you may of lost a connection in between. Will look at schematic to see next tests. Simon C
After looking at Schematic found that the power out of Alternator goes to 50 Amp Breaker part #2759685 then through to battery positive. If you see a 50 amp breaker there in the engine compartment push on the button to see if it resets. Will look for exact location again on schematic. Could be a control of alternator field current that has gone bad, but check that breaker first. Just checked the schematic and it did not have a location for the breaker, but was close to battery most likely. Simon C
See #19 on the attachment. Is this the same pair of fuses that @Cmark showed in Post #6 above.?
Also check the ground cable where it’s bolted to the frame. Had this same problem before and found a loose bolt and corroded connection under all of the dirt.
Thanks everyone for the replies. I think I may have found the issue. There was 2 bare wires that rubbed through on the wiring harness. One went to the starter and the other one I believe went to a dead end plug. I take them up this morning and ran the machine all day. Battery and alternator read 14.5 all day. I am now blowing fuses for the instrument panel. I must have another bare wire somewhere. Thanks again
Yes
Think it was Nige. I only followed the schematic from Alternator to positive post of battery and seen it going through the ( 2759685 ) slow blow fuse on schematic but did not know where it was in terms of location as it was not in blue on the schematic. I am all ears if I missed something. Simon C