Danpatters583 Posted March 7, 2021 Share Posted March 7, 2021 I swapped headlight housings and installed morimoto two stroke 3.0 led bulbs in my 1990. Work great. Only issue is when I turn the car off the drivers side headlight barely stays lit at all times. Its kinda annoying. I was reading on another forum about an led relay harness but no one mentioned any specific type. So I googled it and found a few that look like would work. I was wondering if any one else has had a similar issue and if they used a harness what did they go with? This is what I was looking at: https://www.ebay.com/itm/2x-Headlight-H4-Relay-Wiring-Harness-For-Toyota-95-97-Tacoma-88-95-Pickup-H6054-/333633781689?_trksid=p2349624.m46890.l49292 Link to comment Share on other sites More sharing options...
2seater Posted March 7, 2021 Share Posted March 7, 2021 Amazon.com: 2-Headlight H4 Headlamp Light Bulb Ceramic Socket Plugs Relay Wiring Harness Kit …: Automotive This the harness I used on two different '89's and works great with no splicing. Link to comment Share on other sites More sharing options...
Danpatters583 Posted March 7, 2021 Topic Author Share Posted March 7, 2021 Sweet! Thank you very much. Im adding it to the list right now! I'll let every one know how it turns out once I get it installed. Link to comment Share on other sites More sharing options...
2seater Posted March 7, 2021 Share Posted March 7, 2021 You do need to spend a bit of time sleuthing out the best routing to get adequate length without extensions or cutting. Pick up power at the hot terminal inside the red box by the battery. Remove the steel plate over the top of the radiator to help provide a direct path. It takes a little work but it is worth it. Link to comment Share on other sites More sharing options...
Danpatters583 Posted March 18, 2021 Topic Author Share Posted March 18, 2021 On 3/7/2021 at 12:39 PM, 2seater said: You do need to spend a bit of time sleuthing out the best routing to get adequate length without extensions or cutting. Pick up power at the hot terminal inside the red box by the battery. Remove the steel plate over the top of the radiator to help provide a direct path. It takes a little work but it is worth it. So I finally got a chance to hook that harness up. I hooked it up directly to the red box behind the battery and now I have the opposite problem. My headlights wont shut off.... Any ideas? Maybe the harness I bought is bad? Or possibly bad headlight relay or switch? I bought the exact one you recommended in the above post. Glad I didn't button it all back together again before I tested it. Lol Link to comment Share on other sites More sharing options...
Danpatters583 Posted March 18, 2021 Topic Author Share Posted March 18, 2021 To add, I tried swapping relays around on both the new harness and the "hi/low beam" relay with the park lamp relay in the car and same results. If I turn the light off and pull one of the relays on the new harness the lights shut off. If I plug that same relay I removed back in, the headlights remain off until I turn them on again. So im wondering if maybe I have a headlight switch issue? Or can bad splices underneath all the carpet and stuff cause the same issue? I do have a few interior lighting issues im assuming due to the splice issue from the factory. I have not taken the yet to confirm if they are bad but if its a possibility at this point I might as well tear everything out and repair them Link to comment Share on other sites More sharing options...
2seater Posted March 18, 2021 Share Posted March 18, 2021 Hmm, I haven’t used the harness with led’s but as a booster for the standard lights. It is normal for the doors to close immediately and the bulbs to go out after several seconds since the drain signal is through the relay coil. Do the headlights close but remain on or does nothing happen when deactivated? Hopefully Daves89 may have some input as he has used led headlights with the harness Link to comment Share on other sites More sharing options...
2seater Posted March 18, 2021 Share Posted March 18, 2021 (edited) I don’t believe the under seat splices will cause headlight issues. I wish I had access to one of the cars with the harness but it is still stored fifty miles away. If memory serves, there is a single male headlight plug that plugs into one of the stock headlight plugs but if so, I don’t remember which side it may be connected? The reason I mention this is the original headlight wiring connects to the drivers side bulb and then crosses over to the passenger side. It is not uncommon for one or more of the wires near the headlight, primarily drivers side, to have broken conductor inside the outer covering. It is more common if the headlight wiring is routed incorrectly. As weird as that sounds, it is possible the right side headlight won’t work properly if the wire is broken on the left side. If the harness activation plug is on the passenger side, check with a meter or test light that both hot terminals actually ground through the ground of the plug. Pull the plug back away from the moving headlight doors. The harness relays should only be activated through that male plug. Edited March 18, 2021 by 2seater Link to comment Share on other sites More sharing options...
Ronnie Posted March 18, 2021 Share Posted March 18, 2021 Once the harness is installed the power from the headlight switch only serves a trigger voltage to pickup the harness relays and keep them picked up as long as the headlight switch is on. Make sure you have the harness ground wire making a good connection to ground so the relay will work properly. Here is how I would start troubleshooting this problem. Turn on the headlight switch to pickup the harness relays - that should make the LEDs burn. Then turn off the headlight switch. If the LED headlights keep burning, unplug the plug that connects the harness to the original factory wiring. The LEDs should turn off. If they turn off there is a problem with the original wiring that is supplying power to the harness relays even when the headlight switch is turned off. If the LEDs do not turn off there is a problem with the harness. 1 Link to comment Share on other sites More sharing options...
Ronnie Posted March 18, 2021 Share Posted March 18, 2021 Sorry, I hadn't read 2seater's last post when I wrote mine. He gave some good information on troubleshooting too. Link to comment Share on other sites More sharing options...
Danpatters583 Posted March 18, 2021 Topic Author Share Posted March 18, 2021 26 minutes ago, 2seater said: I don’t believe the under seat splices will cause headlight issues. I wish I had access to one of the cars with the harness but it is still stored fifty miles away. If memory serves, there is a single male headlight plug that plugs into one of the stock headlight plugs but if so, I don’t remember which side it may be connected? The reason I mention this is the original headlight wiring connects to the drivers side bulb and then crosses over to the passenger side. It is not uncommon for one or more of the wires near the headlight, primarily drivers side, to have broken conductor inside the outer covering. It is more common if the headlight wiring is routed incorrectly. As weird as that sounds, it is possible the right side headlight won’t work properly if the wire is broken on the left side. If the harness activation plug is on the passenger side, check with a meter or test light that both hot terminals actually ground through the ground of the plug. Pull the plug back away from the moving headlight doors. The harness relays should only be activated through that male plug. I can't test the headlight motor function at this time because the motors are stripped out. So I have them up permanently until i get a chance to rebuild them. I have them hooked up to the drivers side plug. And yes it is only one plug. I am un certain if the wire harness is broken or not. I will have to dig into it some more. Link to comment Share on other sites More sharing options...
Danpatters583 Posted March 18, 2021 Topic Author Share Posted March 18, 2021 7 minutes ago, Ronnie said: Once the harness is installed the power from the headlight switch only serves a trigger voltage to pickup the harness relays and keep them picked up as long as the headlight switch is on. Make sure you have the harness ground wire making a good connection to ground so the relay will work properly. Here is how I would start troubleshooting this problem. Turn on the headlight switch to pickup the harness relays - that should make the LEDs burn. Then turn off the headlight switch. If the LED headlights keep burning, unplug the plug that connects the harness to the original factory wiring. The LEDs should turn off. If they turn off there is a problem with the original wiring that is supplying power to the harness relays even when the headlight switch is turned off. If the LEDs do not turn off there is a problem with the harness. That is exactly what i did and option one is the case. The lights stay on when the switch is off. So that confirms my suspicion of the factory harness being broken or partially broken. Time to break out the meter. It might be a while before I post on this again. Its supposed to get cold again out here. So I'll post back when it warms up and I get a chance to play with it. Link to comment Share on other sites More sharing options...
Ronnie Posted March 19, 2021 Share Posted March 19, 2021 The problem is likely the headlight switch. When the '88-'89 switches get dirty is is common for them to stick in the on position when you push the off button. Mine did that back when I firs got my Reatta. The next time you test it and the LEDs stay on, turn the headlight switch on and off several times and see if the LEDs finally go off. Don't push to hard though. You can break the switch if you over do it. Link to comment Share on other sites More sharing options...
2seater Posted March 19, 2021 Share Posted March 19, 2021 I know the 1990 headlight switch is sort of an orphan being used only the one year and they do have a history of acting up. I burned up two expensive switches with uprated hi wattage bulbs and mine didn’t have have the mid year addition of the relay to take the load from the switch. The harness has been used to take the load with the side benefit of providing full voltage to the bulbs. Then Daves89 found it also allowed the headlight doors to operate properly with led bulbs without permanent modification. Link to comment Share on other sites More sharing options...
Danpatters583 Posted March 19, 2021 Topic Author Share Posted March 19, 2021 3 hours ago, 2seater said: I know the 1990 headlight switch is sort of an orphan being used only the one year and they do have a history of acting up. I burned up two expensive switches with uprated hi wattage bulbs and mine didn’t have have the mid year addition of the relay to take the load from the switch. The harness has been used to take the load with the side benefit of providing full voltage to the bulbs. Then Daves89 found it also allowed the headlight doors to operate properly with led bulbs without permanent modification. 3 hours ago, 2seater said: I know the 1990 headlight switch is sort of an orphan being used only the one year and they do have a history of acting up. I burned up two expensive switches with uprated hi wattage bulbs and mine didn’t have have the mid year addition of the relay to take the load from the switch. The harness has been used to take the load with the side benefit of providing full voltage to the bulbs. Then Daves89 found it also allowed the headlight doors to operate properly with led bulbs without permanent modification. I will have to try looking at the switch. Before I buttoned everything up a few hours ago I was kinda torturing the harness on the drivers side by bending it and kinda playing around with it to see if it would shut off and no change. So I'm unsure at the moment. I'll report back when I can with updates. Link to comment Share on other sites More sharing options...
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