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Pete, Technician
Category: Classic Car
Satisfied Customers: 28793
Experience:  17 years automotive training and experience.
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When I step on my brakes my interior lights come on. I

Customer Question

When I step on my brakes my interior lights come on. I replaced my instrument cluster with LED bulbs. I have a 74 Chevy, is this an alternator issue? I also lost my brakes.
JA: Have you checked the vehicle's manual for this?
Customer: It is a 74 Chevy C10, I don't have a manual
JA: Are you fixing your C10 yourself? What have you tried so far?
Customer: All I did was replace the bulbs in the instrument cluster to LED. Driving the car and the lights inside flickered and now are not working. When I step on the brake the inter dome and floor light comes on
JA: Anything else you want the mechanic to know before I connect you?
Customer: nope.
Submitted: 10 months ago.
Category: Classic Car
Expert:  Pete replied 10 months ago.

My name is ***** ***** I am a professional here at Just Answer. I noticed that your question had not received a response and thought I would see if you still need help with this.I apologize for the delay and I hope I can still assist you with this here.My info is somewhat limited on your model here but I had seen no one else has responded and would like to see if I can help here.If at any time you feel that I cannot help with this please let me know.

This can be an issue with a ground fault to the electronics.Check the ground at the battery as well as leading from the battery to the engine and frame and body.If a fault is found with loose or corroded grounds this will need repaired.If this is all found to be o.k. it can be the resistance difference in the LED lights causing this fault and you may need a bypass resistor installed to correct this here.

If more help is needed, use the reply tab to continue our conversation. If no further assistance is needed, kindly rate my service,your 5 star rating is appreciated.You can rate at any time and we can continue to work on your question as this will not close out your question.Keep in mind in some cases it can be difficult to fully diagnose or help repair your vehicle without seeing it and I work on delivering the best possible answer from what I see to work with.

Thanks Pete

Customer: replied 10 months ago.
Here is exactly what transpired...1. replaced all 9 dash bulbs with LED bulbs
2. Took truck out at night, lights and radio was on
3. heard a little alternator squeal
4. headlights dimmed at idle
5. under power (driving) dash lights and radio flickered
6. lost all dash and brake lights
7. dome light came on, when I turn off the lights and I press the brakes the dome and courtesy light come on
Expert:  Pete replied 10 months ago.

Just to be sure here this issue occurred after the LED lights were installed am I correct?