lighting issues

tsupra89 · 09-06-2007, 12:54 AM

ok my name is travis and i just started the forum. i have recently replaced my engine and transmission. in my 89 toyota supra T and my lights are wanting to do something strange that i have never seen before ok.

here is how i slove the problem, when i take the dome fuse out of the engine panel the lights work perfect and the headlight motors and all that and the horn, well when i put the dome fuse back into the panel the lights go haywire. if i turn them to the off position on the multifunction switch the lights turn on and vise versa. and the motors wont work and my horn wants to stay on all the time. well i was wondering if anyone has run into this problem and if so hit me up with some info please.

carfanatic89 · 09-06-2007, 01:09 AM

I think it has to be a wire that is grounding out. Just check the wires and see what you find. Thats about all you can do. Or just leave the fuse out. lol

abhattan · 09-06-2007, 02:15 AM

Check along the circuit that the dome fuse is part of and like he said, check to see if there is anything shorting out. Shouldn't be that hard. I would first look in the engine bay where all the recent work was done. Get a manual for the car. This car has alot of circuits that are intermingled. All because of the damn integration relays it has.

mrnickleye · 09-06-2007, 03:22 AM

http://www.cygnusx1.net/Supra/Library/TEWD/MK3/

dannydavi · 09-06-2007, 04:04 AM

i had a similar problem... kinda.. i used to push my horn and it would activate my lights ?!!?!! didnt know for the life of me what was causing it but didnt mind it cause dont use my horn anyways, anyways it ended up just being wrong fuse in wrong place in in the under hood fuse box.. so maybe even making sure all fuse slots are filled with right fuses i guess, good luck.

cre · 09-06-2007, 05:38 AM

Go ahead and test the line for a short to ground. The difficult part of troubleshooting that particular circuit is the number of devices which receive power from it (clock, radio, security system...).

The first thing I think of after reading your post is the security system.

tsupra89 · 09-06-2007, 06:01 PM

the car doesnt have a security system. but i think that the dome circuit is getting a feed. a positive so when i make a connection by putting a fuse in the slot, well it completes that feed and makes everything go haywire. thanx for the responds guys i appreciate it and i hope to talk and help yall to alright thanx agian

cre · 09-06-2007, 08:41 PM

All USDM MKIIIs came from the factory with a security system installed. I've seen it diagnosed as the reason for lighting issues as well (either due to a poor removal job or a fault in the unit). The main reason I'd check the security system is because it integrates with the retractor control/integration relay #2. If the security system was removed I'd go through and verify all the wiring modifications.

tsupra89 · 09-06-2007, 08:58 PM

cre when i got the car there wasnt a security system in it and all the wiring was working properly. this happened after i replaced the engine the integration of the wiring is fine i think i just cross refrenced some wries and its making it feed into the dome fuse. its not blowing my fuse so its not making things go crazy so i think its something like my head light (rh) & (Lh) is intwined with the dome fuse so im gonna check that next time im at my shop. but i do thank you for your smarts and knowledge on helping try and figure it out. i know all us supras came with a security but from factory you can get the security feature tooken out its a added feature that if you didnt want to pay for you didnt have to. just like the targa top. but i thank you agian for your response and i will def keep your knowlegde in mind

cre · 09-06-2007, 09:37 PM

Ok, sorry, you'd just be surprised how many people think they didn't come with one simply because they just never payed attention.

I've never heard that you could special order a MKIII without a security system. I'm going to have to look into that further. If anything I suspect that's just something the dealer offered as the is no p/n for a wiring harness without provisions for the various components, nor are any of them flagged as options in the EPC from Toyota.

If the head lights come on but don't rise when you install the dome fuse a short across either the feed for the headlight relay coil or across both HL fuses is a possibility (the relay's more likely).

If they pop up and turn on then it's either a short across the green wire with the red stripe which runs from the switch to pin #3 of the Integration Relay #2 or the line which used to run from the Integration Relay #2 from the former stock security system (yellow with a blue stripe).

Of course there are other possibilities, I'm just trying to point you in the direction of the most likely candidates.

09-06-2007, 12:54 AM	#1
tsupra89 3" Exhaust Join Date: Sep 2007 Location: asheville Posts: 71	lighting issues ok my name is travis and i just started the forum. i have recently replaced my engine and transmission. in my 89 toyota supra T and my lights are wanting to do something strange that i have never seen before ok. here is how i slove the problem, when i take the dome fuse out of the engine panel the lights work perfect and the headlight motors and all that and the horn, well when i put the dome fuse back into the panel the lights go haywire. if i turn them to the off position on the multifunction switch the lights turn on and vise versa. and the motors wont work and my horn wants to stay on all the time. well i was wondering if anyone has run into this problem and if so hit me up with some info please.

09-06-2007, 03:22 AM	#4
mrnickleye 1000whp postwhore Join Date: Jun 2005 Location: Mojave Desert, Calif. Posts: 1,705	http://www.cygnusx1.net/Supra/Library/TEWD/MK3/ __________________ Had a Red 1989 N/A. Automatic. Sports Pkg. w/wing. TEMS, and some nice MODS. Sold to a friend 10/08/08.

09-06-2007, 04:04 AM	#5
dannydavi 12psi boost Join Date: Mar 2007 Location: Sacramento, Ca Posts: 373	i had a similar problem... kinda.. i used to push my horn and it would activate my lights ?!!?!! didnt know for the life of me what was causing it but didnt mind it cause dont use my horn anyways, anyways it ended up just being wrong fuse in wrong place in in the under hood fuse box.. so maybe even making sure all fuse slots are filled with right fuses i guess, good luck. __________________ '86.5 Supra - A/T - N/A - JDM Useful Sites: ToyoDIY.com ToyotaPart.com MKIIITSRM

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09-06-2007, 01:09 AM	#2
carfanatic89 3" Exhaust Join Date: Apr 2007 Location: Waco Posts: 164	I think it has to be a wire that is grounding out. Just check the wires and see what you find. Thats about all you can do. Or just leave the fuse out. lol

09-06-2007, 02:15 AM	#3
abhattan 3" Exhaust Join Date: Oct 2006 Location: Brentwood, New York Posts: 162	Check along the circuit that the dome fuse is part of and like he said, check to see if there is anything shorting out. Shouldn't be that hard. I would first look in the engine bay where all the recent work was done. Get a manual for the car. This car has alot of circuits that are intermingled. All because of the damn integration relays it has. __________________ '91 Turbo Targa 5 Spd. '87 Corolla GT-S 5 Spd '91 Accord Daily Driver 5 Spd Soon to be rebuilt (All to some extent)

09-06-2007, 05:38 AM	#6
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	Go ahead and test the line for a short to ground. The difficult part of troubleshooting that particular circuit is the number of devices which receive power from it (clock, radio, security system...). The first thing I think of after reading your post is the security system.

09-06-2007, 06:01 PM	#7
tsupra89 3" Exhaust Join Date: Sep 2007 Location: asheville Posts: 71	the car doesnt have a security system. but i think that the dome circuit is getting a feed. a positive so when i make a connection by putting a fuse in the slot, well it completes that feed and makes everything go haywire. thanx for the responds guys i appreciate it and i hope to talk and help yall to alright thanx agian

09-06-2007, 08:41 PM	#8
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	All USDM MKIIIs came from the factory with a security system installed. I've seen it diagnosed as the reason for lighting issues as well (either due to a poor removal job or a fault in the unit). The main reason I'd check the security system is because it integrates with the retractor control/integration relay #2. If the security system was removed I'd go through and verify all the wiring modifications.

09-06-2007, 08:58 PM	#9
tsupra89 3" Exhaust Join Date: Sep 2007 Location: asheville Posts: 71	cre when i got the car there wasnt a security system in it and all the wiring was working properly. this happened after i replaced the engine the integration of the wiring is fine i think i just cross refrenced some wries and its making it feed into the dome fuse. its not blowing my fuse so its not making things go crazy so i think its something like my head light (rh) & (Lh) is intwined with the dome fuse so im gonna check that next time im at my shop. but i do thank you for your smarts and knowledge on helping try and figure it out. i know all us supras came with a security but from factory you can get the security feature tooken out its a added feature that if you didnt want to pay for you didnt have to. just like the targa top. but i thank you agian for your response and i will def keep your knowlegde in mind

09-06-2007, 09:37 PM	#10
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	Ok, sorry, you'd just be surprised how many people think they didn't come with one simply because they just never payed attention. I've never heard that you could special order a MKIII without a security system. I'm going to have to look into that further. If anything I suspect that's just something the dealer offered as the is no p/n for a wiring harness without provisions for the various components, nor are any of them flagged as options in the EPC from Toyota. If the head lights come on but don't rise when you install the dome fuse a short across either the feed for the headlight relay coil or across both HL fuses is a possibility (the relay's more likely). If they pop up and turn on then it's either a short across the green wire with the red stripe which runs from the switch to pin #3 of the Integration Relay #2 or the line which used to run from the Integration Relay #2 from the former stock security system (yellow with a blue stripe). Of course there are other possibilities, I'm just trying to point you in the direction of the most likely candidates.