Hello All. Been awhile but having a rather strange issue and not sure how to attack/trouble shoot it. 1998 SR5 4Runner. headlights just "came on". Check of the headlight switch on the column and it was in the OFF position. Cycled the light switch, side marker/parking lights came on, tail lights came on, both headlights on. Cycled back to OFF, All lights went off except the headlights. Check of the fuse box and pulled the Left HL 10A fuse, left HL stayed on, pulled Right HL fuse both went out. Put only the Left HL fuse in and the Left HL came on, removed it went out. Put in only the Right HL fuse, Right HL came on, removed and it went out.

Not sure why the first time I pulled only the left fuse it did not go out but it slightly dimmed but stayed on. It did go out when the Right fuse was pulled. Both are out at this time but if either fuse is replaced alone, it's accompanying light comes on. Column switch was in the lights off position during fuse removal. I do not believe the column switch is the issue as when the door is opened there is no indication of the switch being in a position to cause a warning alarm, only when the switch is placed in PARKING or HEADLIGHT position do I get a warning alarm.

Not sure what could be the cause, and I can not determine if there is a problem with wiring, connectors or some other explanation. It may be a column switch issue, but I do not have indications of power being routed through that switch in the OFF position as if it is, I should be getting a warning alarm. Thanks for any and all comments or if you have had this issue ple4ase advise on your solution.

 

This issue suggests an electrical fault. Given the symptoms:
- Headlights staying on despite the switch being in the OFF position
- Fuse pulling tests indicating a possible short circuit

Check for:
- Wiring harness damage or corrosion
- Faulty or corroded connectors
- Short circuits in the headlight circuit
- Possible relay or module failure

Consult a wiring diagram and inspect the headlight circuit. Consult a professional mechanic If you're not comfortable with electrical troubleshooting..

 

Thanks for the suggestions. I do have the Electrical volume of the FSM so I can use that to identify the points you mentioned. The only other thing I have done to the headlights is I did replace the left HL with an LED bulb and power module. I had issues with the right side and ended putting the OEM bulb back. I will see if the cable for the connections for the LED harness has been compromised. Just been attempting to determine how power is getting to the lights while bypassing the HL selector switch on the steering wheel.

 

Sounds like the headlight relay welded itself closed,

 

Looking at the electrical diagram I was thinking. Jist waiting for a break in the weather to test out that theory. Thanks for the second set of eyes to help confirm.

 

is the vehicle running, in park and the handbrake pulled while they are "On"? (Have to ask)

 

When the lights were discovered as being ON, everything was static, in Park, light switch was off, hand brake was not pulled. The vehicle is currently NOT running, turned off key removed, Transmission in PARK hand brake is NOT pulled as I don't want the rear drums "welding" to the pads! We have been having some serious rain of late and just picked up a new headlight relay so will be testing the relay failed theory. Also if you check my initial testing I ended up- pulling the headlight 10A fuses. so this way the battery did not get discharged.

 

Gotta break in the weather. Went to NAPA and found the replacement headlight relay. Was bit spendy ($27) so pull the headlight relay, inserted the two 10 amp fuses, plugged in the new HL relay. No headlights coming on, so turned them on and we have a solved issue. Thanks for the aids to troubleshooting to those with suggestions. You all helped me to confirm the issue before replacing things that didn't need to be replaced. On the bright side (ha ha) I located a pair of headlights/lenses at a local Pick and Pull, 1999 4runner and both of the lenses had LED bulbs installed. Was able to get the complete pair of lights/lenses for $10 (big holiday sale) But I will start another thread as I do have some questions and issues.

Thanks to the responders to my previous thread. Be safe out there remember, "Life is a journey, don't forget to pack a bag" ritz

 

Sounds like the headlight relay welded itself closed,

 

Yes, it appears that was theissue as the new relay fixed the issue.

 

Don't mind jamender, it's just a spambot that digs up old threads and repeats one of the comments form it.

For some reason.