The NS switch is a neutral start relay on our coach. From the circuit description, you will see a dedicated circuit breaker behind the white bay breaker panel the flows start battery current directly to Allison through another breaker by the front door panel. Allison flows current to neutral start relay coil, to close relay points when ignition is on and transmission is in neutral. The ignition key start position flows current through close relay points to the aux start solenoid that you manually tripped to run starter.
| STARTER |
| Wire Code | Description |
| B5 000 | Big cable from battery to starter solenoid large terminal |
| B14 2RD | Big cable on start solenoid goes to rightmost isolator terminal |
| ISOLATOR |
| Wire Code | Description |
| B14 2RD | Big cable from starter solenoid |
| B15 2RD | Large cable to 90-amp circuit breaker on bay wall panel |
| B26 RD | Wire to aux start solenoid on isolator panel aux start solenoid |
| BAY WALL PANEL BREAKER |
| Wire Code | Description |
| B15 2RD | Large cable from isolator to leftmost 90-amp big round start battery circuit breaker's lower terminal |
| B69 | Wire from 90-amp breaker to 30-amp ATEC circuit breaker on bay wall panel |
| C6 RD | 10-gauge wire from 30-amp ATEC breaker to front door panel |
| FRONT DOOR PANEL BREAKER |
| Wire Code | Description |
| C6 RD | Wire from bay wall panel to leftmost 10-amp ATEC-ECM circuit breaker located on top-row |
| 136 WH | Wire from 10-amp breaker to Allison ECM interface-plug RD# 136A & 136C, “unswitched batt +” |
| ALLISON ECM COMPUTER |
| ECM computer is located behind carpeted side panel to the left of driver's left foot |
| Wire Code | Description |
| 136 WH | Wire from 10-amp breaker to both terminals RD# 136A & 136C, labeled “unswitched batt +” |
| 123 PU | Wire from ECM terminal PU# 123, labeled “neutral safety”, indicating transmission is in neutral, to neutral safety relay |
| FRONT DOOR PANEL RELAY |
| Wire Code | Description |
| 123 PU | 12-volt positive from Allison, when transmission is in neutral will close #86 coil on neutral safety relay |
| Green ground | Completes #85 coil circuit on neutral safety relay located 2nd from bottom on right side of panel |
| 122 WH | Ignition key momentary start position flows start battery current to neutral start relay #30 common terminal |
| E9 WH | Ignition key current flows from N/O #87 relay terminal to aux start solenoid located on isolator panel |
| ISOLATOR PANEL SOLENOID |
| AUX START solenoid is leftmost of the two solenoids and is located in center of isolator panel above air cleaner |
| Wire Code | Description |
| E9 WH | Ignition key current flows through neutral start relay to small coil terminal on the aux start solenoid, coil is internally grounded to case |
| B26 RD | Start battery current flows from isolator terminal through aux start solenoid when solenoid is closed (by ignition momentary start) |
| B25 RD | When aux start solenoid is closed start battery current flow to starter solenoid coil to activate engine starter, coil is internally grounded |
| IGNITION RELAYS |
IGNITION DUAL-RELAYS are large cube-shaped and are mounted to lower center of front door panel
REMOTE STOP RELAY is positioned lying loose in bottom center of front door panel |
| Wire Code | Description |
| 103 WH | When ignition key is turned on, 103 WH flows start battery current through secure-switch to remote-stop relay #30 common terminal and through NORMALLY-CLOSED #87A terminal |
| 103A WH | To dual-ignition-solenoid coils to close ignition relays, which allows start battery current to flow to ALL ignition circuits |
| REAR ENGINE REMOTE START PANEL |
| Wire Code | Description |
| E21 WH | Ignition circuit breaker #19 located in front door panel powers remote start system start & stop momentary push button switches |
| E23 WH | Pushing remote start switch powers ignition key start wire E22-WH to turn starter on (same as turning ignition key to start positon) |
| E61 WH | Pushing remote stop switch powers remote stop relay #86 coil, opening relay and turning 103A-WH power off to ignition dual-relays |
| Green ground | Completes #85 coil circuit on remote stop relay |
When remote stop relay is powered, 103A-WH power from ignition key is disrupted, turning off ALL ignition circuits MOMENTARILY, which kills power to engine fuel shut-off solenoid, thus stopping engine letting up on remote stop switch allows ignition dual-relays to again close, as ignition key is still on.
First thing I would do, with ignition key off, is to put 12-volts to the small control terminal on the start-solenoid mounted near the isolator. This will close the start solenoid which will send power to the control terminal on the starter-mounted solenoid, which lets very high current to flow from start battery bank to starter motor. (12 volt source is available on isolator side terminal)
If this works, is does not indicate what the problem is, it just tells you all is well with your starter, Foretravel start solenoid, start battery bank and heavy battery cables. This is a simple and important test which tells you if the problem is in the low-current up front section or in the heavy current back section.
From my engine start wiring flow write-up you will find that there is a relay on the front panel that sends voltage to the isolator-panel start solenoid when Allison is in neutral and ignition key is in start position. A meter on the relay wires will indicate if Allison is sending its neutral voltage and if ignition key is sending its start position voltage.
