Why doesn't cruise control work at night when headlights are on?

Engine compartment

Toyota Matrix - fuse box - engine compartment

Instrument panel

Toyota Matrix - fuse box - instrument panel

Fuses (type A)

Fuse Ampere rating Description 1 FOG 15 Front fog lights 2 HEAD LH UPR 10 Left?hand headlight (high beam) 3 HEAD RH UPR 10 Right?hand headlight (high beam), high beam indicator light 4 SPARE 30 Spare fuse 5 SPARE 15 Spare fuse 6 SPARE 10 Spare fuse 7 ETCS (1ZZ?FE engine with two?wheel drive models only) 10 Electronic throttle control system 8 AMP 30 Car audio system 9 MAIN 30 Starting system, "AM2" fuse 10 DOME 15 Car audio system, clock, personal lights, interior light, trunk light, open door warning light, wireless remote control system 11 HORN 10 Horn 12 HAZARD 10 Emergency flashers, turn signal lights 13 EFI 15 Multiport fuel injection system/sequential multiport fuel injection system, emission control system, "EFI" fuse 14 ALT?S 5 Charging system 15 HEAD LH LWR 10 Left?hand headlight (low beam) 16 HEAD RH LWR 10 Right?hand headlight (low beam) 17 EFI2 (1ZZ?FE engine with two? wheel drive models only) 15 Multiport fuel injection system/ sequential multiport fuel injection system, emission control system 18 TAIL 15 Tail lights, license plate lights, instrument panel lights, instrument cluster lights, clock 19 OBD 7,5 On?board diagnosis system 20 WIPER 25 Windshield wipers 21 AM2 15 Charging system, multiport fuel injection system/sequential multiport fuel injection system, starting system, SRS airbag system 22 STOP 15 Stop lights, high mounted stoplight, anti?lock brake system, shift lock control system, multiport fuel injection system/sequential multiport fuel injection system, cruise control system 23 DOOR 25 Power door lock system, glass hatch opener switch 24 AM1 25 "CIG" fuse 25 ECU?IG 10 Electric cooling fan, anti?lock brake system, traction control system, vehicle stability control system, brake assist system, shift lock control system, cruise control system 26 RR WIPER 15 Rear window wiper 27 A/C 10 Air conditioning system 28 INV 15 Power outlet (115 VAC) 29 P/POINT 15 Power outlet (12 VDC/ in the rear console box) 30 ECU?B 10 Daytime running light system 31 CIG 15 Power outlet (on the instrument panel) or cigarette lighter, car audio system, clock, power rear view mirror control, shift lock control system 32 GAUGE 10 Gauges and meters, air conditioning system, daytime running light system, charging system, auto anti?glare inside rear view mirror, power windows, cruise control system, rear window defogger, back?up lights, front passenger's seat belt reminder light 33 WASHER 15 Windshield washer, rear window washer 34 M?HTR/DEF I?UP 10 Engine control system

Fuses (type B)

Fuse Ampere rating Description 35 ABS NO.1 30 Anti?lock brake system, vehicle stability control system, traction control system, brake assist system 36 RDI FAN 30 Electric cooling fan 37 ABS NO.2 40 (without vehicle stability
control system) Anti?lock brake system 50 (with vehicle stability
control system) Anti?lock brake system, vehicle stability control system, traction control system, brake assist system 38 HEAD MAIN 40 "HEAD LH UPR", "HEAD RH UPR", "HEAD LH LWR" and "HEAD RH LWR" fuses 39 AIR PUMP 50 (1ZZ?FE engine with four?wheel drive models and 2Z ?GE engine only) Emission control system 40 HTR 40 Air conditioning system 41 DEF 30 Rear window defogger, "M?HTR/DEF I?UP" fuse 42 POWER 30 Power windows, electric moon roof

Fuses (type C)

Fuse Ampere rating [A] Description 43 ALT 100 Charging system, "ABS NO.1", "ABS NO.2", "RDI FAN", "FOG", "HTR", "AM1", "POWER", "DOOR", "ECU?B", "TAIL", "STOP", "P/POINT", "INV" and "OBD" fuses WARNING: Terminal and harness assignments for individual connectors will vary depending on vehicle equipment level, model, and market.

There is a computer that controls all those things. IT is called the BCM, it is bad. They are not cheap.

Strange electrical problems can sometimes be attributed to a bad ignition switch. The battery should also be load tested, especially if it is more than 4 - 5 years old.

there is a module that controls all those things (usually under the left kick panel). Check with a dealer, or under dodge forums.

Check the fuses, I am not sure if the 1990's had a headlight relay or not (My 1987 Cabriolet does not) but if there is a head light relay its by the battery, if there is one, put your ear down by it and have someone turn the headlights on, you should hear a click.

Also, the turn signal switch/cruise control switch, pull it forward towards the steering wheel and see if the lights come on. If the headlights come on when you pull that assembly towards the steering wheel I am thinking you have a bad headlight switch.

Hope this helps your out. I know the diagram and locator is a bit blurry but hopefully it gets what you need.
Drivers kick panel:
Front wiper 20A - Front wiper system Cigar 15A- Cigarette lighter Audio 10A- Audio, remote control mirror Air Bag 10A -Air bag diagnostics Stop lights- 15A -Rear brake light, high mounted stop light ECU B+ 10A - Shift lock actuator, transaxle controle module, radio, engine control module Room 10A - Interior light, clock, ignition key reminder, rear cargo area light switch ABS 10A- Anti lock brake system control unit ECU IG1 10A - Transaxle control module, shift lock actuator, ABS control unit, DRL unit Meter 10A - Instrument panel, back-up switch, electronics time control module, inhibit switch Turn signal 10A- Hazard switch ,front and rear turn lights, turn indicator IGN1 20A - Ignition switch ABS 30A- ABS pump motor TNS 30A- Tail light, license plate light COOL/FAN 30A- Cooling fan Cond/Fan 20A- A/C condenser fan Starter 15A- Start signal , Fuel pump Blower 25A- Blower Motor SR/ACC 10A - Ignition switch Hazard 15A - Hazard and turn signal light D/Lock 25A- Door locks ABS 30A - Anti lock brake system control P/W RH 20A- Power window motor right hand P/W LH 20A- Power window motor left hand IGN2 25A- Ignition Switch
Engine compartment :
Head 25A- headlights IG 2 30A- Ignition switch IG coil 15A -Ignition coil, condenser,generator IC regulator, diagnostic connector. O2 down 10A- Rear O2 sensor O2 up 10A- Front O2 sensor Fuel pump 10A -Fuel pump unit Injector 10A -Fuel injector ,camshaft positioning sensor, purge solenoid valve, EVAP, IAC actuator, Mass Airflow sensor, EGR stepper motor. fuel pump relay coil, vehicle speed sensor. A/Con 10A - A/C compressor controls, cooling fan BTN 30A- Brake light , high mounted stop light. Tail light LH 10A- License plate light, tail light , rear combo light, instrument panel illumination Tail light RH 10A-License plate light, tail light , rear combo light, instrument panel illumination Head low 15A- Headlight Head Hi 15A-Headlight Horn 15A- Horn

Inside kick panel

It is your Multi function turn signal / Cruise control switch. Dealer will charge you $300 approx. to replace.

hi poss one or both brake light bulbs filaments are touching causing a back feed note if the brake lights are on the cruise control is cancelled

where to find the fuse that controls the headlights

there is a fuse for the cruise control in the fuse box under the hood located right behind the battery. if the fuse is fine, then one of the cruise control components might be bad.

as for the headlight, you might need a new headlight socket. they are easy to replace and the replacement sockets can even be bought at walmart.
if the socket doesnt fix your problem, then you might need a new bright light switch