You don't need the 555U , there is a keyless bypass module for the 99 RX300 that we sell. Here is the wiring diagram that you need:
| ITEM | WIRE COLOR |POL| WIRE LOCATION |
| 12V|WHITE/ blue |+ |ignition harness |
| STARTER|BLACK/ white |+ |ignition harness |
| IGNITION|BLACK / YELLOW |+ |ignition harness |
| SECOND IGNITION|black |+ |ignition harness |
| ACCESSORY|pink |+ |ignition harness |
| POWER LOCK|see direct fax | | |
| POWER UNLOCK|document # 1070 | | |
| PARKING LIGHTS +|green | |drivers kick panel *1 |
| PARKING LIGHTS -|GREEN/ red | |steering column |
| HEADLIGHTS|RED / blue |- |steering column |
| DOOR TRIGGER|RED / white |- |steering column *2 |
| DOME SUPERVISION|same as doors | | |
| TRUNK/HATCH PIN|WHITE/ red |- |drivers kick *3 |
| HOOD PIN|RED / blue |- |*4 |
| FCTRY ALARM ARM|arms with lock | | |
|FCTRY ALRM DISARM|disarms with unlock | | |
| DISARM NO UNLOCK|blue/silver dots *7 |- |steering column || TACHOMETER|orange | |right of the fuse box *5 |
| SPEED SENSE|violet/white | |*6 |
| BRAKE WIRE|GREEN / WHITE |+ |at switch |
| HORN TRIGGER|WHITE/ red |- |steering column |
| WIPERS|blue/blk - blue/red |+ |steering column |
| LF WINDOW UP/DN|red - green |A |in door at motor |
| RF WINDOW UP/DN|red - green |A |in door at motor |
| LR WINDOW UP/DN|red - green |A |in door at motor |
| RR WINDOW UP/DN|red - green |A |in door at motor |
| SUN RF OPN/CLOSE|not recommended | | |
| SUN ROOF LIMIT|not recommended | | |
| RADIO 12V|WHITE/ blue |+ |at radio |
| RADIO GROUND|brown |- |at radio |
| RADIO SWITCH|gray/red |+ |at radio |
| RADIO ILLUMINATE| | | |
| POWER ANTENNA|black |+ |at radio |
| LF SPEAKER|pink - purple | |at speaker or amp *8 |
| RF SPEAKER|lt.green - blue | |at speaker or amp *8 |
| LR SPEAKER|black - yellow | |at speaker or amp *8 |
| RR SPEAKER|red - white | |at speaker or amp *8 |
Notes:
NOTE: This vehicle has an immobilizer system that needs to be bypassed when adding remote start. Use PKT bypass module *1 Located in a gray 15 pin plug. *2 This wire goes to the key cylinder illumination ring and reads the delay. *3 Located in a 20-pin plug, low in the kick panel. Test only with a digital multi-meter as some of the multiplex wires in the car are WHITE/ red. *4 In the engine compartment, under the relay box on the drivers side in a gray 17-pin plug, pin #1 *5 In a 10-pin plug. *6 Coming from the cluster to the cruise control computer, it is located just above the drivers main fuse/relay box.
*7 This is the ignition key sense wire. Using the status output wire from the remote start to ground this wire will disarm the alarm without unlocking the doors. *8 The amplifier is under the rear seat.
Jeff
Velocity Custom Home Theater
Mobile Audio/Video Specialist
Morden, Manitoba CANADA