Generac — CTTS 600-2600 Amp: Switch Will Not Retransfer to Utility
Testing & diagnosis · Contactor Assembly (CTTS 600-2600 Amp)
From a Generac service manual — check it applies to your exact model before use.
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Before you start
- Disable generator from starting; disconnect negative battery cable.
Procedure
- Remove cover. Refer to Figure 1 for PCB layout.
- For testing, follow PCB numbering in Figure 2.
- Test utility trip coil. Measure resistance between PCB2 J1-1 and J1-3. Compare with chart. If good, proceed.
- Test BTS limit switch. Measure resistance between BT1 and PCB2 J2-1. Measure resistance between BT2 and PCB2 J2-2. Less than 4 ohms. If INFINITY, replace BTS limit switch (071345).
- If both tests 2 and 3 favorable and switch not tripping to neutral, replace PCB2 (082428).
- If switch tripping to neutral but not closing to utility, and utility voltage at A1 (126) and A2 (110), test utility closing coil. Measure resistance between PCB1 J1-7 and J1-8. Closing coil resistanc
- Test AX limit switch. Measure resistance between A1 and PCB1 J2-6. Measure resistance between A2 and PCB2 J2-5. Less than 4 ohms. If INFINITY, replace AX Limit Switch (071345).
- If steps 5 and 6 favorable, replace PCB1 (082428).
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- less than 4 ohms
- INFINITY
Source: Generac service manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.