Tail Lamp Failure Module Information

[CRE]

Okay, this little component can be a major bugger to deal with in a number of circumstances. I may do a writeup on rebuiling them, but for now lets start with covering the stock values and modifying it to work with lighting that's different than stock.

There are two resistors which set the trigger values, we'll refer to them as R1 and R2.

I'd like to get some folks to post up the values of these resistors and which year and model they came from (include if the wing uses lamps or LEDs).

Unfortunately, I know very little about the two I have (and I haven't looked at the one in my car yet).

Here are the details from the housing and the resistor values:

Both housings have the same info:
89373-32120
068800-0872
12v 27Wx5, 8Wx4

from '88?
R1 = 24K re,ye,or
R2 = 35K or,gr,or

from '89+ (exact year unknown)
R1 = 22K re,re,or
R2 = 51K gr,br,or


Modification:
If you're running an N/A and you've added a wing you can either replace the resistors with those listed in this thread.

OR (and this goes for those installing LED replacement lamps in place or bulbs) you can install 2 100Ω 1/4W potentiometers and adjust them until the failure lamp no longer comes on. If you don't want to leave the pots in place you can remove them after the value has been found, measure the resistance and install resistors of the appropriate value.

 

[Stu_22]

What if you want to just get rid of it

 

[CRE]

What if you want to just get rid of it

http://www.supracentral.com/index.php?option=com_content&task=view&id=35&Itemid=42

 

[KeithH]

What I want to know is who was the brilliant mastermind that designed the failure circuitry for this box.

Taillight Failure Sensor
1. If a taillight goes out put up an indicator on the dash
2. If the sensor goes out do not allow the brake lights to function AND put NO indicator on the dash!

WTF?!? BRILLIANT!

 

[Supracentral]

What I want to know is who was the brilliant mastermind that designed the failure circuitry for this box.

Taillight Failure Sensor
1. If a taillight goes out put up an indicator on the dash
2. If the sensor goes out do not allow the brake lights to function AND put NO indicator on the dash!

WTF?!? BRILLIANT!

LOL. I never thought of it that way, but it's sadly true.

 

[T701jz]

That's the cops job. He tells you that your break lights are not working (ticket) then you know....:biglaugh: Oh yeah the blue and red lights are the indicator.

 

[KeithH]

I actually had this happen. I was lucky enough to have someone catch me on the offramp (not a cop) and let me know that my brake lights were not working.

 

[CRE]

Does anyone have some of these that they can use to provide some known values?

 

[jetjock]

Been 17 years since I modded mine to work with a custom strobe I replaced the CHMSL with. I used a decade box to find the resistance needed. That strobe is long gone but the LFM was never returned to stock. Fwiw they fail in a certain way that can be prevented by strengthening a particular current path. That said mine hasn't been touched in 17 years and still works fine, other than I don't think it'll tell me if the CHMSL is out. The only mod ever done to it was the resistor change.

 

[CRE]

The path with the jumper closest to the receptacle?

 

[suprabad]

I'm not totally clear on this.

Do we know what resistor values we need to run LED's and not get the "tailights out" light???

Please post and let me know !!!

 

[jetjock]

I'll have to look. I think it's the one on the right, the one with the jumper. I need to look at the schematic. As I said it's been a looong time. The monitoring circuit itself usually doesn't fail, the high current path to the lamps does. Btw see those loops? They're test points.

 

[CRE]

I'm pretty sure that's the one, it's supplied by pin #10 (taillight circuit).

 

[CRE]

I'm not totally clear on this.

Do we know what resistor values we need to run LED's and not get the "tailights out" light???

Please post and let me know !!!

You could solder in two pots and adjust them until it doesn't come on any more. Then if you want to put in a regular resistor just measure the value of the pot and find the closest E24 value. I don't think the system is sensitive enough demand a closer match than 5%.

EDIT:
EIA Standard resistor value tables here: http://www.logwell.com/tech/components/resistor_values.html

 

[Doward]

CRE, I've got two - my stock '88 one (which I'm not sure if it works - as it just constantly said one of my bulbs was out, when it WAS NOT - though that may have been from increased resistance due to corrosion - I never really looked much further into it)

I've also got an '89 one that had the LED wing.

Let me pop them open, see what I have -

'88) 12v 27Wx5, 8Wx4

R1 = red-red-orange-gold = 22k +/- 5%
R2 - green-brown-orange-gold = 51k +/- 5%

'89) 12v 27Wx4, 8Wx4,(LED)
The circuitry on this one is put together differently than the module for the non-LED spoilered '89+ There is only R1

R1 = orange-black-orange-gold = 30K +/- 5%

Do you need a pic of the circuit board?

 

[3p141592654]

Well, the LED center light basically removes one 27W bulb (1156) from the circuit. Hence the 27Wx4 instead of 27Wx5 designation.

The four taillights are 8W each, so we have the 8Wx4 for them on all models.

Note that an 1157 bulb draws 2.1A at 12.8V for the stop filament, and 0.59A at 14V for the tail filament.

So, for an LED turbo, the sensor expects to see 8.4A for the stops, and 2.4A for the tails.

For an N/A, the currents are 10.5A stops, and 2.4A tails.

CRE, your 89+ module since it is 89373-32120 did not come off a turbo, so it is (in principle) identical to the 88 one.

From the EPC
89373-32120 is the 86-92 non-turbo sensor

89373-14050 is the -88 turbo sensor
89373-14070 is the 89+ turbo sensor

Can you provide the part number for the ICs? Presumably they are just comparators.

 

[jetjock]

Each burn out resistor denotes a channel. As 3p said each channel is a comparator circuit with one side connected to a reference voltage and the other connected through the burn out resistor. The output of each channel is connected to an OR gate. The output of the OR gate drives a transistor that controls the warning light. Pretty simple.

Each channel has a delay circuit of .5 seconds. The stop light channel has a latching circuit to keep the warning light on after the brake pedal is released. Don't hold me to it but I seem to recall a failure of the LED CHMSL on cars that have it will not be detected. I could be wrong though.

The Surpa has a 2 channel LFM, one for the stop lights and one for the tail lights. Toyota offers several types of these things with channels for headlights, license plates lights, etc. The USDM Supra didn't get the "best" one. In fact the Supra didn't get several electrical goodies found on some Toyotas of that era.

 

[Doward]

So do we have any way of diagnosing this little beast? I'd LOVE for my taillight failure module to work correctly.

TSRM says:
http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?Section=BE&Page=27

If it's got voltage, but there is still a problem, then replace it.

 

[jetjock]

Doward, open it up and look for toasted paths. Also be sure it's getting power on pin 2 when the key is on. If the ICs are good it should be easy to repair. That said I often see the things on ebay for cheap.

 

[suprabad]

I'm working on this one too. So please keep posting with whatever you guys find!!! (I wanted to give this a bump so it doesn't get forgotton)

Can you imagine how many guys are running around with their tail lights mickey-moused??? This thread is worth the time!