FastCars99

I'm rather confused, does the 1992 Lexus SC300 have CANBUS? 3 wire? 2 wire? How would I know? I've had some trouble trying to find where a service manual exists for a 1992 Lexus SC300 because it seems lots of collectors resell them for hundreds of dollars.

When I try the Lexus Website, it only shows specific sections of what seems to be the owners manual. Any idea? I know it doesn't have ODB, but does my car use CANBUS? Am I going to need a load resistor to mimic a normal bulb due to CANBUS? (Cars with a ECU that detects a low-wattage bulb assume that the bulb is bad, and turn off power. Only to realize that the wattage goes "up" as the voltage decreases, which then causes the power to turn back on.. thus creating a endless loop of on/off causing flickering..)

Wiki and searches only bring up CANBus bulbs.. but not what version of CANBus is used, or if it's used at all with the 1992 Lexus SC300. Thanks for any reply

99SC42

iTrader: (44)

http://en.wikipedia.org/wiki/CAN_bus

SC doesn't have Can bus.

KahnBB6

iTrader: (5)

OP, the 1992-2000 SC's use many individual ECUs and relays for all functions. I believe CanBus may have begun with the 2001+ SC430 which had multiplex ECUs to cover many functions at once but I will stop short of stating that even the 430 models used CanBus.

These cars, though complicated, handle OEM and aftermarket wiring the old fashioned way.

Ali SC3

iTrader: (10)

these cars are very basic obd1 and 96+ is obd2. its not an audi where everything is canbus.

99SC42

iTrader: (44)

Inifiniti G35 has can bus, and I think my 02 GS300 also has can bus.

Ali SC3

iTrader: (10)

that probably makes those models harder to swap, wonder how those guys get the vvti gte swaps in there so cleanly. I can't say I haven't thought about building one I like the model GS you have. throw in a manual swap at the same time that could be a real fun sleeper.

99SC42

iTrader: (44)

98-2001 GS300 is easy since it's not Can bus, 02+ is pita you will lose a lot of functions.

Yeah G35 are a ***** to swap unless you are building a race car.

Kris9884

iTrader: (7)

Canibus, where??

Carista

Huh? CAN is a communication protocol, it has nothing to do with how bulb resistance is detected. I mean, maybe the thing that detects it can communicate over CAN to another ECU to tell it about what it has detected, but that has nothing to do with the detection itself. The communication could use any protocol... like K-line (ISO-9141) for example.

CAN is a relatively new protocol... I think the earliest occurrences of it that I've heard of are from the mid-90s. And it's NOT used on the diagnostic OBD port on any Lexuses before 2006. Older Lexuses use ISO-9141 or variants thereof for OBD diagnostics.

Also, it's OBD (On-Board Diagnostics), not ODB (Ol' Dirty Bastard)

FastCars99

I work in Surface Mount Technology on prototyping new types of hardware that haven't come out yet. Thus making this very interesting to me. There is no CANBUS, correct. As far as I can tell, it's a custom chip that Lexus made that functions similar to a ODB/CAN-based technology. In this case the manual from lexus's website says "Front turn signal lights" bulbs "1157 NA", "27/8" wattage. If the wattage doesn't match, the lexus tends to blink rapidly when turning to indicate that the bulb is not pulling enough wattage to be working properly. (Which is the case with more efficient LEDs that use a great deal less amperage.)

I have been working on this for quite some time now. It seems that these cheap 1157 style sockets are soldered directly onto PCBs, in my case my "$25" MSRP race sport "RS-1157-A-LED" (30k hours) can be had for considerably less on alibaba. I'm assuming where Race Sport, and other manufacturers buy in bulk very cheap electronics.

BOM (Bill of Materials)
1x Leaded solder, with flux. (Probably 60/40, or 63/37 Sn/Pb solder)
1x THM carbon film resistor as 1/8th watt 240 ohm 5% accurate.
5x SMD carbon film resistor as 1/8th watt 240 ohm. (1206 size)
18x 4-pin "High Flux", "HB Electronic Component" 130 deg flat top, P/N 913MY8C
2x circular PCBs (3 layer maybe..) with white silk screen.
5x rectangular PCBs (3 layer?) with white silk screen.

Typical voltage on the normal bulbs is rated at 12.8V to 14V. I'm assuming since the defective bulb has what seems to be a "Fast acting", and a "Slow acting" filament, that is why it's 27/8. (35 Watts total, @12.8 V, ~2.73 Amps) Additionally rated for what seems to be 5,000 hours.

Apparently the forward voltage is 3V to 5V, current requirement is 70 milliamps, 75mW passive dissipation.. but in the circuit they design 37mW of LED dissipation. Which is 0.803 Watts compared to the stock 35 Watts used by normal bulbs. The datasheet suggests 1,000 hours at 20mA, but the manufacturer suggests 30,000 to 50,000 hours when using rated current, and more if using less. (In this case it's 10.5 mA per LED)

If I was to improve the circuit.. I'd probably create a thermal shutoff LED Driver IC with multi-channel control. I think it's somewhere around $2 for those. The LEDs are 10 cents each. The resistors are about 5 to 15 cents each. (Cheaper when using resistor networks, although double wattage capacity is highly desired.)