Revisit: Light Failure Sensor & Cruise Control

[norbertk]

I've been trying to fix the endless list of electrical malfunctions that have been plaguing my car.

Starting with my Light Failure Indicator. I checked all the fuses inside and under the hood, and all are OK. I went in and replaced all bulbs on the taillights and the high mount, as well as cleaned all the connectors with contact cleaner. I tested the voltages, and see no significant interruptions. I took apart the Light failure sensor, as well as cleaned the wire harness, and still haven't had any success. I attempted to inspect the stop light switch under the dash, but couldn't for the life of me get it unconnected. I'm afraid that if I remove the brake pedal spring and the nut, I'll screw it up. Why did they have to mount it there?? In any case, it only goes on once I actually press down on the brake pedal, so I'm figuring it's the root of the problem.

I could take my cluster out and just remove the damn bulb, but this might lead into my second problem with the cruise control.

I've gone through the signal checks with the cruise control, and all diagnosis are normal. While driving it indicates that it's functioning normally.

I'm hoping that the stoplight switch problem is resulting in the cruise control not working, per the wiring diagram. I also jumped the Te1 and E1 and got a flashing O/D light, which I've gathered is the speed sensor. If that was malfunctioning I wouldn't be able to get a speed on my speedometer, no? I'll try and kill myself tomorrow over the stupid stop switch and hopefully it will solve this. Any other suggestions would be helpful.

[airbus]

[

[wwest]

I've been trying to fix the endless list of electrical malfunctions that have been plaguing my car.

Starting with my Light Failure Indicator. I checked all the fuses inside and under the hood, and all are OK. I went in and replaced all bulbs on the taillights and the high mount, as well as cleaned all the connectors with contact cleaner. I tested the voltages, and see no significant interruptions. I took apart the Light failure sensor, as well as cleaned the wire harness, and still haven't had any success. I attempted to inspect the stop light switch under the dash, but couldn't for the life of me get it unconnected. I'm afraid that if I remove the brake pedal spring and the nut, I'll screw it up. Why did they have to mount it there?? In any case, it only goes on once I actually press down on the brake pedal, so I'm figuring it's the root of the problem.

I could take my cluster out and just remove the damn bulb, but this might lead into my second problem with the cruise control.

I've gone through the signal checks with the cruise control, and all diagnosis are normal. While driving it indicates that it's functioning normally.

I'm hoping that the stoplight switch problem is resulting in the cruise control not working, per the wiring diagram. I also jumped the Te1 and E1 and got a flashing O/D light, which I've gathered is the speed sensor. If that was malfunctioning I wouldn't be able to get a speed on my speedometer, no? I'll try and kill myself tomorrow over the stupid stop switch and hopefully it will solve this. Any other suggestions would be helpful.

It seems as though we're on the same track here. However, you've gotten into the cruise control issue a lot more deeply than I have. Electrical system troubleshooting wise. Even though ALL the bulbs had seemed fine anyway, I've only replaced the stop tail light bulbs with the longer lasting 1157LL bulbs but not the high mount tail (it seemed fine). I am also suspecting and have ordered the stop light brake switch. I'll hope it's why the cruise won't engage or work. The other possibilitity I had thought of is the cruise control steering wheel's stalk (switch). I can't imgaine the main ECM's going bad but it could I suppose.

Let me know what else that you have determined. Thanks.

Cruise control is typically disabled any time there is a brake light failure.

And you MUST use OEM or equivalent bulbs with equal or greater current draw, NO LEDs, unless you modify the bulb failure sensor. Oftentimes not even the LL, Long Life, bulbs will not "trip" the bulb failure sensor.

Driving around I sometimes see cars wherein the tail lights go slightly dimmer when the brakes lights come on. This is usually a sight of poor chasis ground connection, negative side battery return, at/from the dimming tail/brake light fixtures.

[airbus]

I've been trying to fix the endless list of electrical malfunctions that have been plaguing my car.

Starting with my Light Failure Indicator. I checked all the fuses inside and under the hood, and all are OK. I went in and replaced all bulbs on the taillights and the high mount, as well as cleaned all the connectors with contact cleaner. I tested the voltages, and see no significant interruptions. I took apart the Light failure sensor, as well as cleaned the wire harness, and still haven't had any success. I attempted to inspect the stop light switch under the dash, but couldn't for the life of me get it unconnected. I'm afraid that if I remove the brake pedal spring and the nut, I'll screw it up. Why did they have to mount it there?? In any case, it only goes on once I actually press down on the brake pedal, so I'm figuring it's the root of the problem.

I could take my cluster out and just remove the damn bulb, but this might lead into my second problem with the cruise control.

I've gone through the signal checks with the cruise control, and all diagnosis are normal. While driving it indicates that it's functioning normally.

I'm hoping that the stoplight switch problem is resulting in the cruise control not working, per the wiring diagram. I also jumped the Te1 and E1 and got a flashing O/D light, which I've gathered is the speed sensor. If that was malfunctioning I wouldn't be able to get a speed on my speedometer, no? I'll try and kill myself tomorrow over the stupid stop switch and hopefully it will solve this. Any other suggestions would be helpful.

It seems as though we're on the same track here. However, you've gotten into the cruise control issue a lot more deeply than I have. Electrical system troubleshooting wise. Even though ALL the bulbs had seemed fine anyway, I've only replaced the stop tail light bulbs with the longer lasting 1157LL bulbs but not the high mount tail (it seemed fine). I am also suspecting and have ordered the stop light brake switch. I'll hope it's why the cruise won't engage or work. The other possibilitity I had thought of is the cruise control steering wheel's stalk (switch). I can't imgaine the main ECM's going bad but it could I suppose.

Let me know what else that you have determined. Thanks.

Cruise control is typically disabled any time there is a brake light failure.

And you MUST use OEM or equivalent bulbs with equal or greater current draw, NO LEDs, unless you modify the bulb failure sensor. Oftentimes not even the LL, Long Life, bulbs will not "trip" the bulb failure sensor.

Driving around I sometimes see cars wherein the tail lights go slightly dimmer when the brakes lights come on. This is usually a sight of poor chasis ground connection, negative side battery return, at/from the dimming tail/brake light fixtures.

:chairshot: Looks like your myth on tail light bulbs interfering with the cruise control is debunked here. Take a look at this link. http://gdl-online.com/bulb.html

[norbertk]

In regards to airbus's post, while the bulbs themselves might not interfere with it, it triggers the Light failure sensor, which in turn won't allow the cruise control system to work.

Further, I replaced the stop light switch today and unfortunately no dice, which brings me back to either the light failure sensor or the wiring harness's for the stop lights. I'll have to play around with those later and I'll report back. Unfortunately there is no way to get around the stop light switch failure, as it also controls the clutch lock. I'll also check the cruise control ECU terminals and see if anything turns up. Unless there is a way to also bypass the light failure sensor. :cries:

Here are the two diagrams to show what's going on:

[airbus]

In regards to airbus's post, while the bulbs themselves might not interfere with it, it triggers the Light failure sensor, which in turn won't allow the cruise control system to work.

Further, I replaced the stop light switch today and unfortunately no dice, which brings me back to either the light failure sensor or the wiring harness's for the stop lights. I'll have to play around with those later and I'll report back. Unfortunately there is no way to get around the stop light switch failure, as it also controls the clutch lock. I'll also check the cruise control ECU terminals and see if anything turns up. Unless there is a way to also bypass the light failure sensor.:cries:

Here are the two diagrams to show what's going on:

Yes I see what you're saying. However, also in your top schematic that you've shown, one separate of the cruise control module's (CCM) terminal's goes through that stop light switch AND on to the cruise actuator.

[norbertk]

Cruise Control Actuator is not working.. Dealer wants $1100 for it.. Anyone know a good online scrap yard?

[airbus]

Cruise Control Actuator is not working.. Dealer wants $1100 for it.. Anyone know a good online scrap yard?

Norbert, you've definitely determined it's the cruise actuator? Where's that physically located? Under the driver's side dash? eBay. Do a search on cruise control actuator. Found some on eBay, used but working supposedly. Click on the following. Hope this helps. i.e. http://search.ebay.com/Lexus-Control-Actua...PageNameZRC0022.

[norbertk]

The actuator is located in the engine compartment, to the right of the engine. It's housed in a black plastic box, and is also linked to the throttle position sensor. I hooked up the actuator to my battery, and it clicked, but the control arm did not move. I can send you over the FSM if you'd like.

I also searched ebay and found no 1993 model actuator, the only ones there were for '94. I'm going to have to try a scrap yard by O'Hare sometime next week.

Are you an airbus driver?

[airbus]

The actuator is located in the engine compartment, to the right of the engine. It's housed in a black plastic box, and is also linked to the throttle position sensor. I hooked up the actuator to my battery, and it clicked, but the control arm did not move. I can send you over the FSM if you'd like.

I also searched ebay and found no 1993 model actuator, the only ones there were for '94. I'm going to have to try a scrap yard by O'Hare sometime next week.

Are you an airbus driver?

Norbert,

That link above, you did click on it? Towards the bottom, once there in eBay there was ONE for a '93 ES 300. Isn't that what you needed? $39.99 buy-it-now.

[norbertk]

Got it, Thank YOU! I'll let you know how it goes.

[norbertk]

I put in the new actuator, and still no dice. I tested the actuator, and it accelerates/decelerates fine, unlike my other one. I also unhooked the battery from my car hoping it might clear any error codes from the CC ECU. I'm still under the impression the light failure sensor is still causing it from operating correctly.