Hey all, rookie trying to DIY a head unit upgrade and running into power issues.
Recently got an 84' Blazer S10 in pretty good shape, but the previous owner's no-name head unit wasn't Bluetooth so I wanted to upgrade. The old head unit was having power issues, cutting out power and restarting intermittently.
I installed a new JVC KD-SX38MBT unit and everything seemed to go well with the wiring. I cut out the old harness (which was actually two) and connected the old wires to the new harness with butt splice connectors. Sounded great for the minute that it was powering. It started playing music fine, but then it quickly turned off and restarted same as the old one when the music got loud. I turned the volume down and it stayed on, but could see the display lights on the head unit flickering when the bass hit. I turned on a podcast quietly and it didn't lose power. But any loud music causes it to restart.
Any ideas on a sequence of troubleshooting to zero in on the problem?
A couple other pieces of info:
-I don't think it's an alternator issue because the same thing happens whether running off just battery or with the engine on.
-Both the constant and keyed wires coming from the dash show 12.3v on my multimeter. Under year old battery shows 12.3v off and 14.3v while running. All the grounds that I could find under the hood seem fully intact. Willing to consider Big 3, but don't want to rely on that advice just yet
-One strange thing was when I cut out the old harness, I identified the black ground wire (which tests as ground). But there was another loose black wire that was not connected to the old harness that tests as a ground just the same as the other one. How should I treat these two grounds?
-The previous owner installed a 200v dual outlet inverter and it doesn't work when I plug a phone charger into it, so I'm curious if that's a clue about general power in the truck? Also auxiliary oil and water gauges. Wondering if the 40 year old electrical supply isn't enough for everything, but don't know how to tell.
-Don't know anything about the speakers, but they're some kind of after-market 4x6 front and 6x9 rear. Don't love them, might want to replace if that changes how I should go about things now.
-Truck feels a bit weak on the start and the dash indicator lights are a bit wonky (one turn signal indicator stays lit solid, high beam indicator will switch on and off for no reason).
Before
Before
After (don't mind the cut wires, this was mid undoing my work)
Thanks very much for any help,
Evan
Recently got an 84' Blazer S10 in pretty good shape, but the previous owner's no-name head unit wasn't Bluetooth so I wanted to upgrade. The old head unit was having power issues, cutting out power and restarting intermittently.
I installed a new JVC KD-SX38MBT unit and everything seemed to go well with the wiring. I cut out the old harness (which was actually two) and connected the old wires to the new harness with butt splice connectors. Sounded great for the minute that it was powering. It started playing music fine, but then it quickly turned off and restarted same as the old one when the music got loud. I turned the volume down and it stayed on, but could see the display lights on the head unit flickering when the bass hit. I turned on a podcast quietly and it didn't lose power. But any loud music causes it to restart.
Any ideas on a sequence of troubleshooting to zero in on the problem?
A couple other pieces of info:
-I don't think it's an alternator issue because the same thing happens whether running off just battery or with the engine on.
-Both the constant and keyed wires coming from the dash show 12.3v on my multimeter. Under year old battery shows 12.3v off and 14.3v while running. All the grounds that I could find under the hood seem fully intact. Willing to consider Big 3, but don't want to rely on that advice just yet
-One strange thing was when I cut out the old harness, I identified the black ground wire (which tests as ground). But there was another loose black wire that was not connected to the old harness that tests as a ground just the same as the other one. How should I treat these two grounds?
-The previous owner installed a 200v dual outlet inverter and it doesn't work when I plug a phone charger into it, so I'm curious if that's a clue about general power in the truck? Also auxiliary oil and water gauges. Wondering if the 40 year old electrical supply isn't enough for everything, but don't know how to tell.
-Don't know anything about the speakers, but they're some kind of after-market 4x6 front and 6x9 rear. Don't love them, might want to replace if that changes how I should go about things now.
-Truck feels a bit weak on the start and the dash indicator lights are a bit wonky (one turn signal indicator stays lit solid, high beam indicator will switch on and off for no reason).
Before
Before
After (don't mind the cut wires, this was mid undoing my work)
Thanks very much for any help,
Evan