BOTH TAIL LIGHTS FLASH WHEN LEFT SIGNAL IS ON NEED HELP

77mali wrote:Any splices or tears in the line? Was it ever unconnected from the forward harness?

1973 454 MONTE wrote:make sure you have all 1157 bulbs in the sockets. a 1156 bulb only has one pin and if put in to a 1157 socket will short it out.

if you need new bulbs put in 2357s they are brighter

ant7377 wrote:Did you mess with the wiring harness back there ? It sounds like something is connected wrong.Do you have a wiring diagram? There is three wires going to each socket back there.The power goes to the left side first maybe something is touching around there that could trigger the right side light.

Ghost Rider wrote:Sounds like bad ground. Try grounding to bumper with jumper cables. At least that will tell you where to start.

Mcarlo77 wrote:I'm no electrical engineer, but seems to me that if the hazard lights, right turn signal lights, brake lights, driving lights all work as they should, the problem could be in the turn signal switch?

pila wrote:Bad grounds can make strange things happen sometimes. I've seen dash lights come on with the brakes ! weird..If a dual filiment lamp doesn't have a good ground on one side, it will sometimes back-feed to get a ground from the other side of the lamp, and will be half lit.
The grounds in GM cars, under the dash, are a trouble spot over the years. On the left side of the dash bottom, the bolt/screw that attaches the dash bottom to the door post, which is used as a ground sometimes, can get loose, making for crazy things to happen.

Mcarlo77 wrote:I'm no electrical engineer, but seems to me that if the hazard lights, right turn signal lights, brake lights, driving lights all work as they should, the problem could be in the turn signal switch?

77mali wrote:Was it a loose wire in the switch? Here's how mine is connected @ alt, hope it helps.

laguna55 wrote:now to get my alt charging ,, i have a good alt. 3 wire post on back is to the + on battery then i have the #1 #2 plug on side of alt i think i have the #2 wire going to the back of alt that gos to the + of battery the #1 wire i dont know where to put it. and for a bonus i dont have a meter to ck it .. any ideas

77mali wrote:All three of the wires in the pic go into a junction in the main harness (T). I have not disconnected the harness so, I can't tell you where they end up, sorry. The plastic conduit splits in the rear of the engine and mine is a double junction w/ 2 of the T's. There are several Red wires that go to A/C, fusible link & heater stuff but eventually the harness goes all the way back to fuse junction box. It also leads in other directions for other systems (starter, battery lead, etc). Is yours the original harness? to the car?

77mali wrote:LOL...

Sorry, thought the pic would be self explanatory but yes it is to the nut right next to it in the pic. (Thanks thatfnthing) Was over-thinking the question