No Brake Lights Part 2

[s10spd-racer]

I did some fartin around with looking for the problem of no brake lights in my 97 S10. I eliminated all of the wire harness that didn\'t pertain to the lighting system of the truck. When i check the plug that supplies the power to the rear of the truck I have power for everything there at the plug, left turn, right turn, tail lights, and when you press the brake pedal it has power to the plug. Everything works on the truck turn signals, tail lights but no brake lights. I checked the plug at the rear of the truck and its only for the back up, turn, tail lights nothing for the brake light. There is a white wire that gets power when you press the brake but its not connected to anything. There was a plug for a trailer on it and all the wires for it were disconnected and just hanging. So im not sure if this is where my problem is. Anyone have any ideas?

[EleV8ted]

if you have an ohmeter, unplug the two connecters and see if you have continuity beween them. if you do, check power at the plug. if you still have nothing, check the connector terminals, sometimes they get \"rapped\" and the pins dont touch and make contact. if you get power see if they share a common ground. on my 89 blazer there are a couple different grounds for certain lights. make sure when you check for power everything is hooked up except for what your checking. when checking for ohms or resistance, make sure the power is off and you isolate that circuit. just some words of advice, good luck.

[s10spd-racer]

I haven\'t checked the plugs with an ohm meter yet, There is a wire that doesn\'t go to a plug in the back of the truck, i believe that it went to a trailer plug that isn\'t there anymore. This wire is the only one that has power in the rear of the truck when the brake is pressed. The thing is, it doesn\'t go to anything, or look like it has a place to be. Its a white wire, If you use that wire thats powered up with the brake pedal pressed and touch each of the wires that must have been used for the trailer plug you will get a turn light for one, the other turn on another, tail/license lights with another, and back up lights with another. So something has to be up with these wires.

[sorj]

a lot of people forget that the brake light circuit goes through the steering column harness. It is controlled by the turn signal and hazard light circuits.I have had many people bring me the same problem to find out that the hazard flasher is missing (usually put in place of the burnt out turn signal flasher) and the hazard lights button is turned on causing the problem.

[rlindus]

sorj is right it uses the same circut has the turn and hazard, the element in the bulb is the same for brake and turn. do you still have the trailer conector plugged in the middle? if you do, take it out, they have a tendancy to short. the white wire is probly coming from that trailer conector and is suposed to be a grounded to the chasis. Being that you have power to it when you step on the brakes is a good indication it is shorted.

[s10spd-racer]

On 2004-04-13 00:13, sorj wrote:

a lot of people forget that the brake light circuit goes through the steering column harness. It is controlled by the turn signal and hazard light circuits.I have had many people bring me the same problem to find out that the hazard flasher is missing (usually put in place of the burnt out turn signal flasher) and the hazard lights button is turned on causing the problem.

Now what if my turn signals work ok and the hazard lights work fine also? Do you still think i should change the turn signal flasher???

[sorj]

if i remember right, I used to pull the bed off of the trucks for faster access to the fuel pump for replacement, don\'t the truck have a harness connector for the bed near the cab? Don\'t change flasher if works for the front and dash bulbs. check the harness for problems from cab to rear lights. Also don\'t forget to check the third brake light for shortage and the stoplight switch for open circuit, the stoplight switch has two individual circuits built into it. Hope this helps, sorj almost for got, you said the white wire was hot. Don\'t forget the bed also has a ground strap. Usually if this is broken, it will normally use the stop light circuit for the ground due to the less resistance thru that circuit (bulb element)

[s10spd-racer]

Cool i will try checking the harness for any problems, I also am gonna try what you said about the ground strap. When i removed the fuel tank i think i remember that strap being cut. Oh I do have power to my third brake light, that does work.

[sorj]

now that I slept on it, I think the harness plug is at the rear. If everything works up to the plug(meaning you can disconnect it to test, then your problem is in the bed wiring.If not,don\'t forget the stoplight switch has the third brake light circuit AND regular stoplight circuit separate. Meaning if you take the switch apart(again if I remember right),you will find two separate sets of breaker points. Good Luck, sorj

[s10spd-racer]

Ok im still having no luck with my brake light problem. I think i have to start looking up front for the problem. Being i eliminated the the abs and cruise control and cut they\'re harnesses back to the main firewall inlet, I believe that is where my problem is. Does anyone know what wires would effect the brake lights that went to either or? And if so how can i get these things working.

[sorj]

make it quick for yourself and check the turn signal switch again. you will have power coming from the brake light switch to column . it switches through turn signal switch and splits off in the turn signal switch itself,using the turn signal circuit for the rear circuit. You said the turn signals work, verify you have the stoplight circuit feeding to the turn signal switch.The problem sounds like it is in this area. I think the stoplight circuit is spliced (not running through for the ABS) so make sure you aren\'t grounding out the circuit. To make short work of it all, take a wire from the stoplight energize terminal and run it straight to the turn signal/stoplight circuit like it is supposed to be. Verify which wire it is for I\'am getting to old to remember. Use a wiring schematic for your truck, it should tell you which one. Don\'t forget to check the fuses again/ if you have the ABS fuse out, it maybe your lid to the whole can of worms. Almost forgot, what year is the truck again, for GM used a CHEAP hazard switch design that stuck up dead center of the steering column which always broke or lost tension for the switch (either way broke). Let me know your progress and I\'ll keep checking on you, sorg

[s10spd-racer]

hello, sorry i haven\'t been on in awhile i was sarting to get burnt out on my truck. I am ready to get to it again and find this f*#!ed up brake light problem. It is a 97 by the way

[IceQueen]

hrm you say your third brake light works?

[s10spd-racer]

Hi IceQueen yes I do have my third brake light. I did some messin with it and the problem has to be up front. I checked the harness at the rear of the truck, its a 4 plug harness. That has a 1.right turn

2.left turn

3.parking lights

4.reverse lights

Everything works there, so the problem has to be in the front. There is another harness back there that went to the trailer light plug that has be cut out. That has a wire in it that has power when the brake is pressed but it goes through the 3rd brake light. I also checked the two flashers they were working fine. The brake light switch has to be working because it turns the 3rd brake light on. What next???? im losing it over here.

[tracker]

do you have turn signals out back? the turn sig circuit doubles as the brake lights. hearing this i would check the signal switch it self.

[FordWizKid]

I dont know if anybody has mentioned this or not but they make hydraulic sensors that are like twenty bucks. They go in any where on ur brake lines and turn ur brake lights un as soon as there is more then static pressure. They are like a 2 wire hook up and are very simple. I will be using this my my truck just to save myself some headaches. Just a thought !

[s10spd-racer]

Yes my turn signals do work.

[tracker]

On 2004-05-20 16:26, s10spd-racer wrote:

Yes my turn signals do work.





then you have continuity through the wireing to the back. looking at a schematic the brake circuit also goes to the turn signal switch. if you have power going into the brake switch and coming out when pressed(that is if it is a positive circuit) then i would bet to say tat the wiring between the signal switch and brake switch is screwed. still could be the signal switch is bad. i have seen it a couple of times. worth a check.



now i don\'t have the schematic in front of me but if i remember right that is how it all goes. i do know that it goes through the switch.

[s10spd-racer]

Hello,

I spoke with a member on the phone from this forum that has a 98 s10 that had the same problem that mine has and we tried a couple of things to get my brake lights working that he did to get his to work but we had no luck. We tried grounding out one of the terminals on the DTD light relay but it didn\'t do anything, After that i noticed something. Now when i turn the key forward and the dtd lights turn on they come on ok, they seem alittle dim but when i turn my head lights on with the switch the driver side head light is really dim. That leads me to believe i have a gound issue that i think is causing my problem. Let me know what you think??

[gdmclnh]

Usually when you get lights coming on at odd times and not working correctly it is a ground problem. Especially if the lights are dim and are affected by other electrical loads or other lights being switched on.

[406S18]

I don\'t know if this question has been answered yet but you can see if you took out your brake light switch located near the top of the brake pedal?

[sorj]

did you check the wiring to the turn signal switch like I asked you to? If you have stoplight power going into the column but nothing coming out on the turn sinal circuits for the rear, there is your problem. Remember, there are two separate circuits for the front turn signals and rear. I think, if I remember right, that the newer S10 has a multi funtional turn signal switch which is always giving troubles. Check this very closely, even if you take apart the switch, the contacts are so tempremental that you may not see it to the naked eye. I am almost willing to bet you that is your problem. Don\'t go on wild goose chases, if you have the third brakelight working, and turn signals working for the rear (unless you rewired rear to the front circuits), The problem is going to be in switching circuits. Hope this helps, sorg

[s10spd-racer]

Thank You i will rip into the switch tonite after work and see what i come up with and post asap.

[s10spd-racer]

Ok here the deal, I really tore into it tonite and i think i you guys will be able to finally tell me WTH my problem is with this turd. I checked the white wire from the brake switch to the turn signal switch which is a that supplies power to the switch when the brake is pressed and i have nothing coming to the turn switch. So i checked the power at the switch and it has power. If i run a different power source to the white wire coming out of the brake switch i get brake lights and no third light. But if i use the power inside the brake switch i only get the third brake light to turn on and no brake lights. I checked the brake switch and everything seems to be working ok inside but i don\'t know PLEASE let me know what you thing, i think we are closing in on this problem and now its more a quest then anything to figure out. PLEASE HELP

[s10spd-racer]

One other thing i just checked is that the white white that comes out of the brake switch and goes to the turn signal switch has continuity with a ground.

[Da-Chia]

I am having the same problem - very interested to hear the outcome...





everything works but the brake lights. also the drivers side headlight and drivers side running lights have issues... brights work day cruisers work but regular headlights the drivers side does not...





back to the brake lights

abs is gone and i am assuming the problem is up front like he said.





I am at a total loss when it comes to the wireing and the guys i had do the final wireing really put the screws to me...





I followed all the wires up to the eng comp and they seemed to die where they should ahve ran into the abs unit



95 s10 was a cpi now a tpi

[Da-Chia]

update if anyone is still following:





(Ice queen if your listening you may be my only hope)

ok

what we have found:



all bulbs good

fuses good

harness is fine from the eng comp back to tails 3rd brake light functions fine with pedal switch - as for the tails we disconnected the plug where it ran into the cab at the firewall and directly ran power to the terminals all lights function properly when power is put directly to them so all is fine there -



replaced the brake switch and according to the 3rd brake light is functioning.



Blinkers, hazards, and running lights are perfect still even the reverse lights work...



when tested with a multimeter we found that only one white wire from one of the plugs that went to the abs unit became hot - (abs is gone)



there are 3 plugs for that abs unit and I do not think any of them have any involvement with the funcion of the brake lights them selves any more (as we added power to every terminal in the plugs and none was effected -trial and error) but the white wire we found could operate the brake lights with a bit of afro/redneck ingenuity but this rigging completed a circuit between the 2 tail lights and unwanted side effects of turnsignals making both flash like hazards made this an unfeasable option and was only tested to prove that all was workign in a manner of speaking...



I am down to this point I believe the problem is between the brake switch and the fire wall the wires from the plug if i remeber right are brown, white, orange, and 2 purples total of 5 to the switch. I have not found these wires comming out of the firewall into the eng comp. so I believe that they follow some unknown endless path through the steering column to the hazard switch and then to the relays or something along that route.



if I knew where they went and what they tied into it might be of some help but I am not sure because no matter where they head they are still not working and i need to find wehre to tie in, bipass or whatever it takes to get this thing working.





all help appreciated. (I did not want to start a new thread on this since this seems to be an open issue)



cruise control is gone, abs is gone, 4.3 CPI -> 5.7 TPI conversion ina 95 ls ex cab.



thaniks in advance



Jake B.