Generac — Procedure (9 steps)

For these Generac models: CTTS STYLE CONTACTOR ASSEMBLY 600-2600 AMP, CTTS Style CONTACTOR Assembly (100-400 Amp), CTTS Style CONTACTOR Assembly (600-2600 Amp), CTTS Style Contactor Assembly, W Style CONTACTOR Assembly, Wn STYLE CONTACTOR ASSEMBLY 600-2600 AMP, Wn Style CONTACTOR Assembly (100-400 Amp), Wn Style CONTACTOR Assembly (600-2600 Amp).

Applies to: Generac Ctts Style Contactor Assembly 600 2600 Amp, Generac Ctts Style Contactor Assembly, Generac W Style Contactor Assembly, Generac Wn Style Contactor Assembly 600 2600 Amp

Procedure

1. 7. .
2. 7. Measure the resistance between J1-1 and J1-2. Closing coil resistance should be measured.
3. 8. At this point, if Steps 4 and 5 results were good, the switch should be tripping to the neutral position. If switch is not in the neutral position, push the manual trip button and manually trip the switch to the neutral posi­ tion. With the switch in the neutral position, measure the resistance between A2 and J2-2. A reading of 0.2 ohms should be measured. If INFINITY is measured, replace LS (Part # 074672A). If good, proceed to the following test.
4. 9. Measure the resistance between A1 and J1-1. A read­ ing of 0.2 ohms should be measured. If INFINITY is measured, measure resistance across AX contacts of the AXBX limit switch (Part # 071345). If closed, mea­ sure the resistance between NO/Com (upper/lower) con­ tacts on LS (Part # 07472A). If INFINITY is measured, replace.
5. 10. If results from all steps are good, then replace the PCB (Part # 082428). DRAFT SWITCH WILL NOT TRANSFER TO GENERATOR If the transfer switch will not switch over to genera­ tor power and generator voltage is measured at E2 (AT2)/107 (AT1) and E2 (B2)/234(B1) then proceed as follows: * FROM STARTING. Follow all Safety guidelines and insure that the unit is 100% disabled by confirming that it’s in the “OFF” position, the Main Line Circuit Breaker is in the “OPEN” position and that the “NEGATIVE” Battery Cable is properly disconnected. This must be verified PRIOR to performing this and/or any inspection of moving components.
6. 1. Remove front cover.
7. 2. For the purpose of testing, the PCB layout is shown in
8. 3. If switch is not tripping to neutral, measure resistance between J2-6 and J2-7. The resistance of the trip coil should be measured, +/- 7%. If INFINITY is measured,
9. 4. replace the trip coil. If good, proceed to .
10. 4. Remove the single Phillips head screw holding the PCB in place. Unplug the male to female connector located behind the PCB. Verify the contactor is in the utility measure ohms between the yellow and brown wires 0.2 ohms should be measured. Measure ohms between the orange and gray wires 0.2 ohms should be measured. should now show open or INFINITY. J1 J2 J3 1 8 2 3 4 1 2 3 4 5 3 2 1 4 5 6 7 6 7 looking down) Part 1 Page 12 Troubleshooting Section 1.3 “Wn” STYLE CONTACTOR ASSEMBLY 100-400 AMP DRAFT Troubleshooting Section 1.2 “Wn” STYLE CONTACTOR ASSEMBLY 100-400 AMP Part 1 Page 13
11. 5. At this point, if Steps 3 & 4 results were good, the switch should be tripping to neutral.
12. 6. If switch is not in the neutral position, push the manual trip button and trip the switch to neutral. Measure ohms between J2-4 and J2-5. Select coil resistance should be measured. If INFINITY is measured, replace the select
13. 7. coil. If good, proceed to .
14. 7. Measure resistance between B2 and J3-3. A resistance of 0.2 ohms should be measured. If an INFINITY read­ ing is recorded, replace the PCB or check the solder points and trace on the back of the PBC. If proper resis­ tance is measured, measure resistance between B1 and J2-4. A reading of 1.6 M ohms should be measured. If INFINITY is measured, test the AXBX limit switch.
15. 8. Measure ohms between the back contacts on the AXBX limit switch (blue wires) 0.2 ohms should me measured. If open replace AXBX limit switch. (Part # 071345, locat­ ed on the outside of the contactor assembly). If good,
16. 9. proceed to .
17. 9. At this point, if Steps 6 and 7 results were good, the select coil should be energizing. Test the closing coil. Measure resistance between J2-1 and J2-3. Closing coil resistance should be measured. If good, proceed to
18. 10. .
19. 10. Measure resistance between B1 (J1-3) and J3-2, open or INFINITY should be measured. Manually push down ohms should be measured. If INFINITY is measured, test AXBX limit switch. Verify the switch is still in the neutral position and measure the resistance between the two front contacts with the yellow wires attached to them. A reading of 0.2 ohms should be measured. If and open or INFINITY is measured replace the AXBX limit. If the AXBX limit switch tests good replace the select LS (Generac Part#074672A), which is located inside the contactor assembly to the right of the trip coil. If proper resistance is measured, measure resistance between B2 and J3-1. INFINITY should be measured. Again, push
20. 0. 2 ohms should be recorded. If INFINITY is measured,

Source: manual:Generac GTS Trouble Shooting - 0H3949-A2.pdf. Figures and steps are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.