‘Not Generating Troubleshooting Guide’
1 Engine running; Air pressure built up. Alternator is not charging and "no gen" tell tale light at the dash is on.
Yes Step 2
No Step 26
2 Engine running. Check stud #33 located in the rear electrical box for 12 volts.
Yes Step 9
No Step 3
3 Engine running. Check stud #49 located in the rear electrical box for 24 volts.
Yes Step 4
No Step 12
4 Engine running. Check stud #48 located in the rear electrical box for 6 to 11 volts (voltage depends
on the condition of the batteries and output of the alternator).
Yes Step 52
Stud #48 reads battery voltage (24 volts). Yes Step 53
Stud #48 reads 0 to 5 volts. Yes Step 5
5 Engine stopped; Master on. Remove cover on voltage regulator located in the #3 baggage compartment. Check for 24 volt
power. (On old regulator part #7G-4-1, terminal marked "A1". On new regulator part #07-04-1001, terminal marked
"A1, Ing.")
Yes Step 6
No Step 49
6 Engine stopped; Master on. Check "F1" on the voltage regulator located in the #3 baggage compartment for output voltage.
Yes Step 17
No Step 19
7 Engine stopped; Master off. Remove "F1" wire located in the #3 baggage compartment from the voltage regulator "F1" terminal,
and measure the resistance of the wire to chassis ground. It should read 3 to 5 ohms of resistance.
Yes Step 18
No Step 8
8 Engine stopped; Master off. Remove the "F1" wire located in the #3 baggage compartment from the "FLD" terminal on the
alternator (tape it up and make sure that it is not touching anything). Read the resistance of the "F1" wire. It should
read Infinity.
Yes Step 15
No Step 42
9 Engine running. Check for a ground on pin #7 of the discharge and blower relay located in the rear electrical box.
Yes Step 10
No Step 43
10 Engine stopped; Master off. Check for a ground on pin #7 of the discharge and blower relay located in the rear electrical
box.
Yes Step 11
No Step 24
11 Replace the discharge and blower relay located in the rear electrical box with 12 volt relay part #7D-5-1. Continue
Step 54
12 Go to the field relay located in the rear electrical box and check pins 1 & 8 for 24 volts.
Yes Step 13
No Step 38
13 Go to the field relay located in the rear electrical box and check pins 3 & 6 for 24 volts.
Yes Step 14
No Step 33
14 Go to stud #49 located in the rear electrical box and check for 24 volts.
Yes Step 4
No Step 50
15 Engine stopped; Master off. Remove wire "F1" off the "FLD" terminal on the alternator. Meter the resistance of the "FLD"
terminal. It should meter 3 to 5 ohms of resistance.
Yes Step 16
Open Step 22
Shorted Step 21
16 Engine stopped; Master off; Main disconnect on. Remove wire "R1" off the relay terminal on the alternator. Meter the
voltage of relay terminal. It should be less than 1.5 volts.
Yes Step 11
No Step 22
17 Engine running. Check for 12 volts on stud #33 located in the rear electrical box.
Yes Step 54
No Step 30
18 Engine stopped; Master off. Make sure that wires are hooked back up to the alternator - "F1" to "FLD" terminal and "R1"
to relay terminal. Replace the voltage regulator and put "A1" wire on "A1" or "POS" terminal (with new style regulator,
hook up to "B").
Continue Step 53
19 Check for a ground on "NEG" of the voltage regulator ("G" on the new regulator) located in the #3 baggage compartment.
Yes Step 7
No Step 49
20 Engine stopped; Master off. Remove wire "F1" from the "FLD" terminal on the alternator. Meter the resistance of "FLD"
terminal. It should meter 3 to 5 ohms of resistance.
Yes Step 42
No Step 21
21 Engine stopped; Master off; Main disconnect off. Change out the alternator and the voltage regulator.
Continue Step 23
22 Engine stopped; Master off; Main disconnect off. Change out the alternator.
Continue Step 23
23 After installing new alternator, pull the field relay located in the rear electrical box and run engine for five minutes.
Stop engine and plug in the field relay.
Continue Step 52
24 Prior to unit #47071 - Check for a ground from the low air switch located in the rear electrical box. Effective with
unit #47471 - Check ground studs located in the rear electrical box.
Yes Step 10
No Step 25
25 Prior to unit #47071 - Replace low air switch located in the rear electrical box. Effective with unit # 47071 - Clean
and repair ground studs located in the rear electrical box.
Continue Step 10
26 Push the press to test button and see if the "no gen" tell tale comes on at the dash.
Yes Step 2
No Step 27
27 Replace light bulb (part #19-11-1105) in the tell tale cluster at the dash.
Yes Step 26
No Step 28
28 Engine stopped; Master on. Check for 24 volts on pin #1 of the discharge and blower relay located in the rear electrical
box.
Yes Step 32
No Step 29
29 Check circuit breaker #54 (load side) for 24 volts on the master buss bar located in the rear electrical box.
Yes Step 45
No Step 31
30 Engine running. Check relay terminal on alternator for 12 volts.
Yes Step 10
No Step 22
31 Remove and replace circuit breaker #54 located in the rear electrical box; part #7C-13-127.
Continue Step 28
32 Engine stopped; Master on. Check pin #4 of the discharge and blower relay located in the rear electrical box for 24
volts.
Yes Step 36
No Step 11
33 Engine stopped; Master on. Check for 24 volts on pin #7 on the field relay located in the rear electrical box.
Yes Step 34
No Step 51
34 Engine stopped; Master off. Check pin #2 on the field relay located in the rear electrical box for a ground.
Yes Step 35
No Step 39
35 Check the field relay terminals located in the rear electrical box, and replace field relay, part #7D-5-24.
Continue Step 36
36 Engine stopped; Master on. Check for 24 volts on stud #49 located in the rear electrical box.
Yes Step 54
No Step 12
37 Check for 24 volts on battery buss bar on the load side of circuit breaker "A" (15 amp) located in the rear electrical
box.
Yes Step 46
No Step 40
38 Check for power on circuit breaker "A" (load side) on battery buss bar located in the rear electrical box.
Yes Step 48
No Step 45
39 Engine stopped; Master off. Check stud #47 located in the rear electrical box for ground.
Yes Step 47
No Step 41
40 Remove and replace circuit breaker "A", part #7C-13-127, located in the rear electrical box.
Continue Step 36
41 Remove and replace triple function protective device located in the rear electrical box.
Continue Step 36
42 Repair or replace harness from the voltage regulator to stud #48 located in the rear electrical box to alternator "FLD"
terminal.
Continue Step 18
43 Repair or replace the jumper wire with diode assembly from stud #33 located in the rear electrical box to pin #2 on
the blower discharge and cut-in relay.
Continue Step 54
44 Repair or replace harness from relay terminal of the alternator to stud #33 located in the rear electrical box and F1
terminal of the alternator to stud #48 in the rear electrical box.
Continue Step 54
45 Repair or replace jumper from circuit breaker #54 located in the rear electrical box to pin #1 on discharge and blower
relay.
Continue Step 28
46 Repair or replace the jumper from circuit breaker "A" located in the rear electrical box to field relay pin #'s 8 &
1.
Continue Step 13
47 Repair or replace jumper wire from pin #2 on the field relay located in the rear electrical box to stud #47.
Continue Step 36
48 Repair or replace wire from circuit breaker "A" on the battery buss bar located in the rear electrical box to pin #'s
1 & 8 on field relay.
Continue Step 12
49 Repair or replace harness from stud #49 located in the rear electrical box to voltage regulator "A1" terminal; stud
#48 in the rear electrical box to "F1" terminal on voltage regulator; and ground stud in the rear electrical box to "NEG"
on voltage regulator and jumper to mounting box.
Continue Step 6
50 In the rear electrical box, repair or replace jumper between field relay pin #'s 3 & 6 and stud #49.
Continue Step 36
51 Repair or replace jumper between studs 24 & 25 located in the rear electrical box and pin #7 on field relay.
Continue Step 36
52 Engine running Measure the voltage on "R1" terminal of the alternator for 12 volts.
Yes Step 44
No Step 22
53 Engine stopped; Master on. Check "FLD" terminal on alternator for battery voltage.
Yes Step 15
No Step 44
54 Engine running on fast idle and charging; Head lights and exterior lights on. Check or adjust the voltage regulator
to 27.5 volts.
Yes Step 55
No Step 1
55 Make sure that all clamps, terminals, relays and covers are secured. Job Done