Fuse blowing

[608KEB 795]

I haven't posted any problems for a long time. But my luck ran out. The 25 amp fuse keeps blowing on the 520H. I looked at the wiring diagram. Looks like a possible key switch issue.  It could also be between the starter and the battery. I'll check the connections. Clean them up also. Am I headed in the right direction?

[WHX?? 48,851]

I always start by disconnecting everything downstream of the fuse KEB. Start connecting things back up till she blows again to narrow down where it might be.  Be on the lookout for rubbed thru wires. Let us know what you find.

[953 nut 55,390]

12 hours ago, 608KEB said:

I'll check the connections. Clean them up also. Am I headed in the right direction?   YES

A bit of corrosion or a connector that isn't tight can cause a bit of heat and excess electrical draw. The fuse holders and other components that are near the battery are all subjected to a bit of battery acid during their life and should be cleaned or replaced.

[608KEB 795]

I replaced the + battery cable. The end connecting  to the battery was ready to break off. I checked the voltage  when running

 It's  14.3 volts. I also checked the voltage to the 25 amp circuit  breaker that kept blowing.  It was also 14.3 . Is this correct? Or do I put the multimeter  at a different  setting  to test amperage?

[Guest 88vic]

Looks may be deceiving but that positive post looks a little too close to the battery hold down rod. 

[lynnmor 7,319]

Most multi-meters will not check amps that high, you need a special DC amp meter.  I doubt that an amp meter will help you diagnose the problem.  To blow a fuse, there is a short or something causing an extreme load.

[608KEB 795]

far away

[Tractorhead 9,064]

You Voltage should be ok.

 

To measure the Amps, i would suggest to buy an cheaper Clamp Ammeter.

As a combined multimeter the cost will be about 40-90$ depending on quality.

search i.eg at harbor freight for.  Clamp Amp Meter and you will find a item.

(as far as i know, it‘s not allowed, to place here a Link.) 

 

Important is, it must be able to measure DC Amps, not only AC Amps. 

The AC Amp only versions are typically much cheaper, but didn‘t work for DC.

Please read the Text, that it is definitely also for DC Amps.

sometimes they offer Multimeters with Ac/Dc Voltage and only AC Amps, but in text it will be stupid described.

 

 

The Clamp Ammeter has the advantage, you don‘t have to interrupt you existing cableing, 

the clamp simply will be clamped over the Wire, you wanna measure the Current.

 

Also the Clamp Ammeter can measure mostly up to 600A contactless, what can be a easy used to measure Starter Current while diagnosis on Solenoids, what needs otherwise huge cables and a real big Shunt on direct way.

 

The disadvantage on the Clamp is, that if you wanna measure real small Amps, below 0,5A the accuracy wasn‘t that fine,

but all above 1A current can be cleanly detected, what is in most case accurate enough.

[Macwrench 133]

On 9/21/2019 at 4:50 PM, 608KEB said:

I haven't posted any problems for a long time. But my luck ran out. The 25 amp fuse keeps blowing on the 520H. I looked at the wiring diagram. Looks like a possible key switch issue.  It could also be between the starter and the battery. I'll check the connections. Clean them up also. Am I headed in the right direction?

 

I believe that power wire runs straight from the hot side of solenoid, to the fuse, and to the ignition switch.  Unplug the ignition switch and check it.  Also, does it blow with the switch off or on?  If off, then it's definitely a short.  You can buy reset-able circuit breakers that you can use for troubleshooting.