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2015 Dodge Ram 1500 5.7 Hemi
Diagnosis
2015 Dodge Ram 1500 5.7 Hemi Headlights Not Working After Engine Install
February 21, 2026
V
Visitor Original question
2015 5.7 Hemi. After a new engine install, my headlights don’t work. I think it’s a ground because when I use the turn signal the headlight flashes. I’ve searched all day but can’t find it. Where should I look? I’d rather not take it back to the shop.
Wizuto AI Response
Most likely cause is a bad or missing ground connection for the headlights after the engine swap. The fact the headlights flash with the turn signal is a classic sign the headlight circuit is backfeeding through the turn signal bulb due to a poor ground.
Most likely culprits
- Headlight ground wire or ground point: Often a ring terminal on the body or frame near the headlight assembly or battery. Could be disconnected, corroded, or missing after engine removal.
- Headlight wiring harness connector: Check for damage or misconnection during engine swap.
- Headlight relay or fuse: Less likely but worth verifying power and fuse integrity once grounds check out.
How to narrow it down
- Locate the headlight ground wire(s) near the front of the truck, usually a black wire with a ring terminal bolted to the chassis or body near the headlights. Inspect for tightness, corrosion, or missing bolts.
- Use a test light or multimeter: With headlights on, probe the ground wire terminal at the headlight connector and the chassis ground. If you get no continuity or high resistance, the ground is bad.
- Check for power at the headlight connector with headlights on. If no power, check fuses and relays in the under-hood fuse box.
- Inspect wiring harness connectors around the headlight area for damage, loose pins, or corrosion.
- Temporarily jump a good ground from the battery negative terminal directly to the headlight ground terminal. If headlights light up, you’ve confirmed a ground issue.
Possible parts (if needed)
- Headlight ground wire or ground strap (if damaged or missing)
- Headlight relay (only if power is missing after ground confirmed good)
- Headlight fuse (if blown)
A few questions
- Did the shop disconnect and reconnect any ground straps or wiring harnesses near the front during the engine swap?
- Are both headlights affected or just one side?
- Have you checked the under-hood fuse box for any blown fuses related to headlights?
Fix the ground first. It’s almost always the root cause in these post-engine swap headlight no-power issues.