# 1998 gmc Sonoma brake lights **URL:** \ **Category:** Maintenance/Repairs\ **Created:** [February 9, 2015, 2:38am UTC](https://community.cartalk.com/t/1998-gmc-sonoma-brake-lights/88976 "2015-02-09T02:38:52Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![blake1770](https://avatars.discourse-cdn.com/v4/letter/b/9f8e36/32.png) [@blake1770](https://community.cartalk.com/u/blake1770)\ **Post date:** [February 9, 2015, 2:38am UTC](https://community.cartalk.com/t/1998-gmc-sonoma-brake-lights/88976/1 "2015-02-09T02:38:52Z")
The brake lights on my truck are not working all the fuses are good, the bulbs are good, I have changed the brake switch. They still do not work, altho all the other lights at the rear work even tail lights. Idk im confused ---
**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\ **Post date:** [February 9, 2015, 2:47am UTC](https://community.cartalk.com/t/1998-gmc-sonoma-brake-lights/88976/2 "2015-02-09T02:47:30Z")
Does the high center brake light work? Tester ---
**Author:** ![asemaster](https://avatars.discourse-cdn.com/v4/letter/a/5f9b8f/32.png) [@asemaster](https://community.cartalk.com/u/asemaster)\ **Post date:** [February 9, 2015, 2:57am UTC](https://community.cartalk.com/t/1998-gmc-sonoma-brake-lights/88976/3 "2015-02-09T02:57:28Z")
Somewhere else on this forum there’s a thread lamenting things like brake lights that are controlled by the body computer and wishing that things were simple again like on your truck. If your turn signals work but the brake lights don’t and you’ve verified power at the brake switch and/or replaced it I would suspect a faulty turn signal switch. But I would consult a wiring diagram and test to be sure. ---
**Author:** ![Cougar](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/cougar/32/21348_2.png) [@Cougar](https://community.cartalk.com/u/Cougar)\ **Post date:** [February 9, 2015, 8:36am UTC](https://community.cartalk.com/t/1998-gmc-sonoma-brake-lights/88976/4 "2015-02-09T08:36:56Z")
Try cycling the emergency flasher switch to see if that helps. If the middle brake light isn’t working then there may be some other trouble. You should verify that power is getting to the brake switch, as was mentioned previously. ---
**Author:** ![blake1770](https://avatars.discourse-cdn.com/v4/letter/b/9f8e36/32.png) [@blake1770](https://community.cartalk.com/u/blake1770)\ **Post date:** [February 9, 2015, 10:31am UTC](https://community.cartalk.com/t/1998-gmc-sonoma-brake-lights/88976/5 "2015-02-09T10:31:25Z")
There is power to the brake switch but nothing to the lights. But there is clicking coming from under the dash. ---
**Author:** ![blake1770](https://avatars.discourse-cdn.com/v4/letter/b/9f8e36/32.png) [@blake1770](https://community.cartalk.com/u/blake1770)\ **Post date:** [February 9, 2015, 10:32am UTC](https://community.cartalk.com/t/1998-gmc-sonoma-brake-lights/88976/6 "2015-02-09T10:32:03Z")
The third brake light hasn’t worked since I bought it but I didnt care about that ---
**Author:** ![Cougar](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/cougar/32/21348_2.png) [@Cougar](https://community.cartalk.com/u/Cougar)\ **Post date:** [February 9, 2015, 8:52pm UTC](https://community.cartalk.com/t/1998-gmc-sonoma-brake-lights/88976/7 "2015-02-09T20:52:19Z")
Since you have proven that power is getting to the switch then the most likely suspects for the problem is the emergency flasher switch and the turn signal circuit. The brake circuit has to pass through both of those circuits I believe. See if the emergency flashers work and if so then I suspect that switch is where the problem is at. Cycling the switch a number of times may clear the bad contact. The middle light most likely has burned out bulbs in it and you should check them. ---
**Author:** ![blake1770](https://avatars.discourse-cdn.com/v4/letter/b/9f8e36/32.png) [@blake1770](https://community.cartalk.com/u/blake1770)\ **Post date:** [February 9, 2015, 10:26pm UTC](https://community.cartalk.com/t/1998-gmc-sonoma-brake-lights/88976/8 "2015-02-09T22:26:46Z")
Ok thank you im going to check that I changed that hoping to fix the headlights but seems I caused more problems ---
**Author:** ![knfenimore](https://avatars.discourse-cdn.com/v4/letter/k/9fc348/32.png) [@knfenimore](https://community.cartalk.com/u/knfenimore)\ **Post date:** [February 9, 2015, 10:32pm UTC](https://community.cartalk.com/t/1998-gmc-sonoma-brake-lights/88976/9 "2015-02-09T22:32:00Z")
Switch, then turn signal switch then stop lamp. ---
**Author:** ![missileman](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/missileman/32/1366_2.png) [@missileman](https://community.cartalk.com/u/missileman)\ **Post date:** [February 9, 2015, 10:42pm UTC](https://community.cartalk.com/t/1998-gmc-sonoma-brake-lights/88976/10 "2015-02-09T22:42:02Z")
Make sure that all 3 stoplight bulbs have a good ground. My wife’s 2003 Blazer had this exact problem. I ran a new ground and all brake lights started working. If you check for voltage assuming the ground is good…you can get a zero reading. ---
**Author:** ![blake1770](https://avatars.discourse-cdn.com/v4/letter/b/9f8e36/32.png) [@blake1770](https://community.cartalk.com/u/blake1770)\ **Post date:** [February 10, 2015, 3:37am UTC](https://community.cartalk.com/t/1998-gmc-sonoma-brake-lights/88976/11 "2015-02-10T03:37:18Z")
there is no power getting to the rear brake lights . Im about to check the third light ---
**Author:** ![blake1770](https://avatars.discourse-cdn.com/v4/letter/b/9f8e36/32.png) [@blake1770](https://community.cartalk.com/u/blake1770)\ **Post date:** [February 10, 2015, 3:59am UTC](https://community.cartalk.com/t/1998-gmc-sonoma-brake-lights/88976/12 "2015-02-10T03:59:45Z")
Im lost on this truck every since I bought it its been wiring issue after the other. ---
**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\ **Post date:** [February 10, 2015, 4:12am UTC](https://community.cartalk.com/t/1998-gmc-sonoma-brake-lights/88976/13 "2015-02-10T04:12:51Z")
Try turning on the emergency flashers and see lights in the back work then. Tester ---
**Author:** ![blake1770](https://avatars.discourse-cdn.com/v4/letter/b/9f8e36/32.png) [@blake1770](https://community.cartalk.com/u/blake1770)\ **Post date:** [February 10, 2015, 5:07am UTC](https://community.cartalk.com/t/1998-gmc-sonoma-brake-lights/88976/14 "2015-02-10T05:07:19Z")
Ok third brake light works fine now I replaced the bulbs but still no rear brake lights ---
**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\ **Post date:** [February 10, 2015, 5:17am UTC](https://community.cartalk.com/t/1998-gmc-sonoma-brake-lights/88976/15 "2015-02-10T05:17:19Z")
You need a turn signal/multifunction switch. The high center brake light circuit doesn’t pass thru this switch, but the regular brake lights circuit does. Tester ---
**Author:** ![George\_San\_Jose1](https://avatars.discourse-cdn.com/v4/letter/g/e5b9ba/32.png) [@George\_San\_Jose1](https://community.cartalk.com/u/George_San_Jose1)\ **Post date:** [February 10, 2015, 6:33am UTC](https://community.cartalk.com/t/1998-gmc-sonoma-brake-lights/88976/16 "2015-02-10T06:33:35Z")
How are you determining there’s no power at the light switch? You have to measure using two test points right, one the power and one the ground. Are you using a known-good chassis ground for the ground test point? ---
**Author:** ![George\_San\_Jose1](https://avatars.discourse-cdn.com/v4/letter/g/e5b9ba/32.png) [@George\_San\_Jose1](https://community.cartalk.com/u/George_San_Jose1)\ **Post date:** [February 11, 2015, 6:58am UTC](https://community.cartalk.com/t/1998-gmc-sonoma-brake-lights/88976/17 "2015-02-11T06:58:29Z")
@Tester … I see what you mean by looking at the schematic posted above, just wondering what the manufacturer’s motivation might be to run the brake light circuit through the multi-function switch? Is it so they can use the same bulbs for both the turn signal function and the brake light function? Save on parts count and reduce the amount of wire needed? ---
**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\ **Post date:** [February 11, 2015, 7:03am UTC](https://community.cartalk.com/t/1998-gmc-sonoma-brake-lights/88976/18 "2015-02-11T07:03:42Z")
It serves three functions. Turn signals, brake lights, and emergency flashers. Tester ---
**Author:** ![blake1770](https://avatars.discourse-cdn.com/v4/letter/b/9f8e36/32.png) [@blake1770](https://community.cartalk.com/u/blake1770)\ **Post date:** [February 12, 2015, 3:13am UTC](https://community.cartalk.com/t/1998-gmc-sonoma-brake-lights/88976/19 "2015-02-12T03:13:24Z")
I use a test light with a very good ground. I have now pulled I the dash and…I am looking further into this problem. As I said before there is a clicking noise coming from under the dash ---
**Author:** ![blake1770](https://avatars.discourse-cdn.com/v4/letter/b/9f8e36/32.png) [@blake1770](https://community.cartalk.com/u/blake1770)\ **Post date:** [February 12, 2015, 3:43am UTC](https://community.cartalk.com/t/1998-gmc-sonoma-brake-lights/88976/20 "2015-02-12T03:43:45Z")
I still have all lights but brake lights [Next page](https://community.cartalk.com/t/1998-gmc-sonoma-brake-lights/88976.md?page=2)