Headlights will not illuminate

[Moy]

Hey there folks. Have a 1988 Supra, originally non-turbo/auto, swapped to a turbo/manual. My headlights used to illuminate before the swap, but now they will not.

When I turn the knob on the stalk all the way forward (headlights should turn on), the headlights will pop up but the headlights will not turn on. All of the other running lights and interior lights will turn on.

If I switch the headlight stalk forward to the "high beam" position, the high beams still do not illuminate and the high beam indicator on the dash does not illuminate.

I had removed the headlights when doing my swap, as I was doing some minor front end work as well (nothing electrical). Might this have created a problem?

Using this: http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=BE&P=22

For the headlight control relay. If I jumper pins 1 and 4 or 3 and 4 on the body side, the headlights will turn on. Same if I pop the stalk into the high beam position, the highs and indicator light will illuminate.

I've swapped the relay with 3 others (all same part number), and none have fixed my issue.

I need some help on this matter please.

 

[Moy]

Forgot to add that my taillight failure indicator on the dash is lit... but my turn signals, side indicators, brake lights (brake depressed and not), hazards, and reverse lights all work as they should...

 

[jetjock]

I suggest you use this:

http://www.cygnusx1.net/Supra/Library/TEWD/MK3/manual.aspx?S=Main&P=060

And this:

http://www.cygnusx1.net/Supra/Library/TEWD/MK3/manual.aspx?S=Main&P=18

You must be misidentifying pins on the relay socket. Jumpering 4 and 5 should turn on the lights. Jumpering 1 and 4 will do nothing. Jumpering 3 and 4 with the stalk switch on will destroy the integration relay...

 

[Moy]

I suggest you use this:

http://www.cygnusx1.net/Supra/Library/TEWD/MK3/manual.aspx?S=Main&P=060

And this:

http://www.cygnusx1.net/Supra/Library/TEWD/MK3/manual.aspx?S=Main&P=18

You must be misidentifying pins on the relay socket. Jumpering 4 and 5 should turn on the lights. Jumpering 1 and 4 will do nothing. Jumpering 3 and 4 with the stalk switch on will destroy the integration relay...

Alright. Yes, 4 and 5 does turn on the lights. I have 12 v at 1 and 4, but at 3 I only have 9v. With my understanding (and that of my neighbor who is a master electrician) pin 3 should have 12v at it. Is this correct?

If the integration relay IS fried, what does it look like so I know which to replace?

 

[jetjock]

Well, it'll have 12 volts on it when the headlights are off but it should go to ground when the lights are on. Think about it: how could the headlight relay work with 12 volts on both sides of the coil?

IR #2 is located behind the dash on the left side:

http://www.cygnusx1.net/Supra/Library/TEWD/MK3/manual.aspx?S=Main&P=15

Blue box iirc. That said at least part of it must be working if the lights go up so I wouldn't condemn it just yet.

 

[Moy]

Alright. I went on the theory of poor ground, so I found all of the grounds in the engine bay that I could and clean them, then replaced them. Still no luck.

Hell, I'd be happy with only having high beams, because then I can at least see at night... Haha...

 

[jetjock]

Dunno what to say other than check the wiring and explain how it works:

When at the headlight position the stalk supplies a ground to pin 14 on the Integration Relay. The circuit in the IR turns on the transistor, allowing current to flow through the headlight relay coil into pin 10 on the IR and out to ground via pin 18. This energizes the HL relay.

At the same time the circuit biases on the two other transistors and current flows from the retraction motors into pins 9 and 1, through the transistors, then out pin 18 to ground. This energizes the motors.

See the little arrows on the transistors? Those are the emitters. For the sake of this discussion you can think of them as pointing towards the direction of current flow.

Edit: I should point out if the engine idles up when the stalk is set to headlights on, whether they're on or not, the integration relay is working. Look elsewhere.

 

[Moy]

Ahhh okay I was reading the wiring diagram wrong. So because I have power at the two pins it indicates that that part of my IR is working correctly, but I could have a fusible link or wiring issue between the battery and relay, which won't allow the higher current to flow to the bulbs. Is this understanding (at least partially) correct?

 

[jetjock]

The HL relay is what handles lamp current. For the headlights to work:

a) 12 volts must be on pins 1 and 4. Pin 4 supplies 12 volts to one side of the contact while pin 1 supplies it to one side of the coil. This is the "power side" of the circuit and carries the lamp loads.

b) Ground (supplied by the IR) must be placed on pin 3 to energize the other side of the coil. The coil is what closes the contact and sends power out to pin 5, the fuses, and on to the lights. Pin 3 is the "signal side" of the circuit. It is independent of the power side and doesn't carry lamp loads.

c) The headlights are grounded through the combo switch. This is the "ground side" of the circuit. It also carries lamp loads.

Jumper 4 and 5 with the stalk on. If the lamps light the power and ground side are working. The problem lies in the signal side...the relay is not being energized by the IR. If the engine idles up it's a wiring problem somewhere after the IR and before the HL relay. If there's no idle up suspect the IR...

 

[Moy]

Jumping pins 4 and 5 do turn the lights on.

I've not started the car since the swap as I don't have spark or tach signal (but have a separate thread in the 7M-GTE Tech section for that issue)

 

[jetjock]

Headlights aren't much good on a car that doesn't move. I'd fix the engine first

 

[Moy]

Haha I know JJ, I'm just trying to take care of all my problems at once. I'm waiting on an ignitor, so I figured I'd try to resolve my headlights issue

 

[jetjock]

Fair nuff. If all else fails jack up the radiator cap and roll another car underneath it

 

[Moy]

I bought a spare IR today. 20 bucks. gonna swap it out and see if my headlights work haha

 

[Moy]

Swapped in the new (to the car) Integration Relay and my headlights work great now!

Thanks for your help JJ

Now I need to figure out why I'm still not getting readings on my gauges...