| All values measured to ground unless otherwise noted | |||
| A28/2 | |||
| Antenna amplifier interchanging signals | No reliable test, check continuity of wiring | ||
| A34/6 | |||
| 1.1-10 | Handset to audio module interchanging signals | No reliable test, check continuity of wiring | |
| A59/1 | |||
| A.3 | Main ground to W6 | Approx. 0 Ohms to ground | |
| A.4 | Circuit 30 main power input, supplies CTEL system | 12 VDC at all times | Feed from F1f7 |
| A.5 | Circuit 15R power input | Key in steering lock position "1" 12 VDC | Feed from F1f6 |
| D2B IN D2B OUT |
Optical input port Optical output port |
No reliable test | |
| Note 1 | Phone systems are replaced as whole unit and do not require further maintenance | Check for proper power supply and continuity of wiring | |