Morimoto 35W HID Relay Problem

Stric_IX · July 27, 2018

"Short version"

Headlight bulb went out. Replaced the bulb and it still wouldn't work. After troubleshooting I found out it was a relay. Replaced a relay with a 5 pin 35928 from Advanced Auto and got it working.

"Long version"

I just recently had a problem with the headlights on my truck ('14 GMC Sierra) and discovered that it had the Morimoto kit already installed. My problem was my passenger side bulb was out. So I ordered new bulbs and put them in. Passenger side still didn't work. I swapped ballast from side to side and the PS bulb still wouldn't come on. So I swapped the ignitors, same result. I even checked the voltage at the ballast and was getting 12v at each ballast. Then I ripped the whole kit out and reinstalled it exactly like the Moriomoto instructions called for. The previous owner wired the kit to where everything was installed on the driver side. The instructions call for everything being installed on the passenger side. Not that it makes any difference but it gave me a way to go through and check all connections. After all that I still had the same problem but instead of the PS bulb now it was on the DS bulb. Still getting 12v at both ballasts but the bulb wouldn't fire. Last thing I decided to check were the relays. That ended up being the problem. I was able to get a 5 pin relay from Advanced Auto (listed above) that worked perfectly and it was only $10. Problem solved, headlights now work but I'm not big with electrical stuff so this still has me confused as to why it wouldn't work with the old relay. If the relays are outputting 12v to each ballast then I don't understand why the bulbs wouldn't come on.

I just wanted to share this experience in case someone else ever goes through this with similar problems and give a part number to use if you ever have to replace either of the two relays that come in the Morimoto kit.

dcarl · August 19, 2018

Thanks for posting. I have a same issue with the passenger side misfiring intermittently. I changed the ballast and still had the problem. I just so happened to have a spare harness so I replaced both relays instead of the whole harness. Mine however are 40A 4 pin relays rather than 5 pin relays.

I ordered an additional set of relays on Amazon to have as a backup spare if the issue returns. I've had my kit installed since December of 2015, and this was the first problem I've had other than a bad ballast which TRS replaced under warranty.

njs2247 · August 25, 2018

I had the same problem with my 35w Morimoto HID kit after 1 year of use. I did everything you did only to find out it was one of the relays. Contacted Theretrofitsource.com and they sent me a new one for free under warranty. Then a couple of months later, the other relay went out. Again, they sent me a new for free under warranty. It's been close to 3 years since all that and no problems since (I hope I didn't just jinx myself...)

AhuraPro · August 26, 2018

I had the worst issues with that kit, I documented the problems and TRS made it right. The XB fogs have been a champ but they need to HTFU with a complete XB headlight setup for these trucks like they did the F150.