Xas 97 pops 10 amp breaker when put to position 1?

Questions & AnswersCategory: Air Compresser TroubleshootingXas 97 pops 10 amp breaker when put to position 1?
Joseph Hanselman asked 1 year ago

Hello I have a olde model xas 97 in for service. The breaker that is wired in with the starter switch pops whenever I turn to position 1 . I was told the alternator was rebuilt when it came in.

So far I have removed the alternator and had it rebuilt my alternator service man said without a doubt this alternator had not been rebuilt and it contained diodes that where burnt.

i noticed the diode/rectifier had also been replaced recently with the correct part.

A ground wire that ties into the k5 relay and glow plug had been broke so I replaced it

the wires in the wiring harness had also been damaged in the 86 grounds wires.

i have a xas185 at the shop that I was able to compare wiring harness and relays to. Most matched up except there appears to be three red wires that re not present in the damaged unit that tie into the s4 and starter switch.

Please help…I have exhausted all othe options

best regards JH

2 Answers
Cas Staff answered 1 year ago

Hi JH,

First, I have upload the schematic – I am pretty sure this is the correct one.

You can find a full version here.

You say the fuse blows when you switch to position 1.

In position one, the switch connects only to wire #2 (those numbers are wire numbers, not switch positions, the switch positions are the ‘hamburgers’: the top line of the hamburger is pos 1, the 2nd is pos 2 and the bottom one is pos 3).

So in position 1 power is supplied to:

  • K4 – pin 2
  • K3 – pin 30
  • S6
  • S5

I think probably the easiest thing to check is to remote the wires one by one and see if the fuse still blows or not.

It could be something unrelated to k4 and the alternator.

Let me explain the function of k4: when the motor is stopped, alternator connection D+ has no power – when switching the main switch to position 1, k4 gets power through the main switch – k4 will switch over to connections 30-87.

Now when we turn the main switch to ‘start’ – K0 gets power and the starter motor will start.

As soon as the engine picks up enough speed, The alternator connection D+ will go ‘high’ (12 volt) – this means K4 will have +12 volt at both sides of the coil – making it de-energize! This breaks the connection to the starter relay K0 – and the starter motor is disengaged.

So K4 together with the alternator (connection D+) works as a safety mechanism / automatic starter motor disengagement when the engine has picked up enough speed.5 But, as I said – the problem could very well be somewhere else. it could be a short somewhere else for example.

Please try to 1) disconnect wire from k4 – pin 30 and see what happens. And also 2) disconnect wire from K3 – 30 , or 87a, and see what happens.

Hope this helps and please let me know how it works out or if you find out anything!

All the best,





Jh answered 1 year ago

Well, I have managed to completely learn the whole wiring schematics by memory…I have been able to isolate the wires responsible for the breaker popping, unfortunately no current is sent to the relay to excite it and switch current from 30-87 to 87a. I have pulled the relay and jumped it with satisfactory results. There is definitely a ground issue somewhere in the harness. All switches are bypassed.  Alternator is pushing proper voltage to battery.  Red dangling wire that was cut has been repaired. It goes to s4 and relay for glow plug.  I suppose tomorrow (I have had to knock out other compressors first and can now return to the XAS97) i will begin tracing all wires for a bad ground. I’m guessing this because there is a -6 volt drain on my blue wires that connect to the warning lights and s4.    Thanks for all the help bud!