1987 Toyota Camry -BRAKE (STOP) LIGHTS DO NOT LIGHT

billr

wrench
Staff member
Joined
Mar 12, 2007
Messages
7,268
Points
63
OK, post the two readings you get at the connector (harness); be sure to have "key-on"
 

josiah

Full Member
Joined
Jan 5, 2007
Messages
114
Points
16
billr,
I took a volt-ohm meter reading today:
key-off-readings at connector(brake switch harness)->
SLOT#1->13.12 volts; SLOT#3->0.
Only problem i failed to read your Saturday reply; so I will need to re-do with "KEY ON" (I assume I need to simply turn key so accessories lights come on). Plan to re-do tomorrow. Please pardon my error.

Paulto57509,
Took look in truck but did not find a junction box. Plan to take another look.

grcauto,
I really think the problem is the corrosion in connector (brake switch harness)slot#3. If I could remove harness (without cutting wires) it would be great; and if cleaning the corrosion did not work at least I could eliminate a possibility.

Thanks.
 

billr

wrench
Staff member
Joined
Mar 12, 2007
Messages
7,268
Points
63
Turn the key to the "run" position, where it springs back to after you release it from cranking/starting the engine. I don't expect the readings to change, but let's be sure.

Have you tried jumpering 1 and 3 contacts in the harness together, does that turn on the lights/
 

josiah

Full Member
Joined
Jan 5, 2007
Messages
114
Points
16
billr,
1) I took a voltage meter reading today:
key turned to light dash lights; readings at connector(brake switch harness)->
SLOT#1->12.56 volts; SLOT#3->1.4 volts.
However based on your last reply above apparently I should have turned key all the way to "run". Plan to redo readings tomorrow.

2) Question. When I did turn key to start engine, the engine did not crank. Is this normal when the brake light switch has been removed?

3) Appreciate the jumper idea; plan to try tomorrow.
Thanks.
 

billr

wrench
Staff member
Joined
Mar 12, 2007
Messages
7,268
Points
63
I can't say for sure about this specific type vehicle, but I would not expect the brake switch to have any effect on cranking.

Grcauto, do you have a schematic of the starting circuit to post?
 
Last edited:

JackC

wrench
Joined
Nov 14, 2006
Messages
1,742
Points
48
Location
Nothern California
2) Question. When I did turn key to start engine, the engine did not crank. Is this normal when the brake light switch has been removed?
If you normally need to put the brake on prior to starting, then the switch probably does have to be in play in order to start the car.
 

josiah

Full Member
Joined
Jan 5, 2007
Messages
114
Points
16
billr,
1) I apparently got the readings right the last time.
I took a voltage meter reading yesterday:
key turned all the way to start position; then release key; readings at connector(brake switch harness)->
SLOT#1->12.70 volts;
SLOT#3->1.14 volts.

2) Inserted jumper wire (paper clip) in connector (wiring harness) SLOT#1 to SLOT#3. Brake lights did not light.

billr and JackC,
As far as the engine not cranking I thought I would ask if removal of the switch could be a factor. Just curious.
However right now my main concern is getting the brake lights working. Because the not cranking could be simply due to corrosion on the battery posts; it has happened before.

billr, JackC and grcauto,
As I said before, visually there is corrosion inside connector (wiring harness) SLOT#3. grcauto informed me to use water+baking soda to remove it. The problem is getting the solution in there overnight. And I do not see how to remove the connector. The other problem is I only THINK this may be the problem.

Thanks.
 

billr

wrench
Staff member
Joined
Mar 12, 2007
Messages
7,268
Points
63
If you think you may have battery cable/terminal problems that are preventing cranking, then fix that right away. We don't want to be confusing this thread with symptoms that are not related to the brake switch problem. How about Jack's comment, does this car normally require the brake pedal to be pushed to enable cranking?

Jumper 1 and 3 again (always, key-on...) and read voltage on those wires; you will have to pierce the wire insulation with sewing needles/pins to be sure you are reading voltage on the actual wire conductors. With them jumpered the voltage should be the same, of course. I don't know whether it will be the 12.7 or the 1.14, but am guessing both will go to 12.7 If both wires do have the same voltage, then corrosion is not likely to be a problem, as the wires have been proven to be adequately connected together just the same as supposed to happen through the switch.. By the way, the baking-soda will work in just a few minutes, no need for an overnight soak. I know things are tight where you are working, but try putting the baking-soda solution in a small jar and dangling the harness end into it.

Again, if the jumper (or the switch) can connect the wire conductors so that they have the same voltage, that is the best you can have. No use fussing about corrosion any more. I strongly encourage you to try the switch itself for this "jumpering", since the terminals in the harness may be bent/deformed such that a jumper makes contact with them, but the switch does not...

If we can be confident that the two wires are being connected together, and the lights still don't come on, then we will have to move back to the PCM connector that the wires end at and do similar voltage tests.
 

Mobile Dan

wrench
Joined
Mar 1, 2002
Messages
3,827
Points
48
Location
Kentucky
I recommend you look at the diagram in reply #9 and locate the Light Failure Sensor (grid location 43-D). See that green/white wire at position 7? Jumper pins 1 and 3 at the switch (or just connect connector to switch and put a brick or rod on brake pedal to hold it down) and turn the key on (if necessary). I think that you should have power at green/white wire at Light Failure Sensor (yes, you are going to have to locate the Light Failure Sensor). Do you have power at pin seven?? Remove jumper or release pedal...is the power gone? I think the green/white wire at the switch ends up back in the trunk (green/white wire at position 7) at the Light Failure Sensor.
 
Last edited:

billr

wrench
Staff member
Joined
Mar 12, 2007
Messages
7,268
Points
63
Dan, I am not seeing the connection between that "Lamp Failure Sensor" module shown in reply #9 to the "Brake Switch" in reply #6 that we are discussing. Yes, I see four GRN/WHT wires coming from pin 3 of the switch, but none are labeled as going to the sensor module. Likewise, the GRN/WHT wire at pin 7 of the sensor module is not labeled as going to the switch. Colors are often re-used in wiring harnesses, so we can't rely on them being the same electrical node just by the GRN/WHT.
 

josiah

Full Member
Joined
Jan 5, 2007
Messages
114
Points
16
billr, Mobile Dan and JackC'

billr,
1) Regarding Jack's question->does this car normally require the brake pedal to be pushed to enable cranking?-> No, at least I am reasonably sure that you do not have to press brake to crank engine. When I think about it, as a habit when cranking the engine I put my foot on the brake but this was for safety reasons.
2) I have cleaned around connector slot#3 with old toothbrush; plan to clean with cotton swab+baking powder+water shortly.
3) After cleaning slot#3 plan to try jumping slot#1 to #3 to see if brake lights come on.
3) The connector (wiring harness) slots appear to be undamaged.

Mobile Dan,
1) I plan to look in trunk to see if I can find Light Failure Sensor. I assume it is a box with 7 wires connected; including a green/white wire.
2) I appreciate the video; however already saw it during my prior problem when the brake lights would not go off. Thanks anyway because I may help me in locating the Light Failure Sensor.

Thanks.
 
Last edited:

Mobile Dan

wrench
Joined
Mar 1, 2002
Messages
3,827
Points
48
Location
Kentucky
Josiah
You can check all the wires at the Light Failure Sensor. Consider this strategy...remove connecter from Light Failure Sensor. Test all wires for power when brake pedal is not held down (or connector is not jumpered). Then, press pedal down (or install jumper) and test all wires at Light Failure Sensor again. One of those wires should get powered up when Brake pedal is held down.
Bill
I suspect there are "missing pages" regarding the brake lamp circuit.
Because the Light Failure Sensor provides power to the taillamp bulbs, is stands to reason that "a signal" will come from the brake switch. If Josiah finds that one of the wires the the Light Failure Sensor goes on/off with the brake switch, we will know that the brake switch is working.
 
Last edited:

billr

wrench
Staff member
Joined
Mar 12, 2007
Messages
7,268
Points
63
OK Dan, that makes some sense; although pins 2, 3, and 7 of the LFS are all possibilities for looking for that signal. Agreed, #7 with the GRN/WHT is most likely...
 
Top