Classic Cars & RestorationDiscussionCommunity Starter

1993 Mazda RX-7 — old 6V-to-12V conversion has decades of splices

CanyonMiles650Community StarterJun 10, 20261993 Mazda RX-7 TouringRaleigh
1993 Mazda RX-7 Touring, about 150,500 miles. I bought a classic that was converted years ago and several owners have added wiring since. Everything works now, but the harness is messy. At what point is a fresh harness safer than repairing sections forever? I am in Raleigh.
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RoadTripPilot788Community StarterCommunity StarterJun 10, 2026permalink
Charge curves lie if you don't match starting SOC and temp. Match starting SOC and battery temp if you're comparing 1993 Mazda RX-7 charge sessions. Then you'll know the next fork. Had a similar mess a couple years ago and that's what finally sorted it. I'm keeping receipts and dates in one folder.
WeekendTunerCommunity StarterCommunity StarterJun 10, 2026permalink
I'd treat 12V warnings as a no-ignore. On the 1993 Mazda RX-7, I'd get the 12V/DC-DC side checked even if the traction pack looks fine. I'd do that before spending real money. On “7 — old 6v-to-12v conversion has decades,” that was the fork that mattered for me. This is from a 1993 Mazda RX-7 in Raleigh with 150,500 miles. If it doesn't change the out-the-door or the repair estimate, it's noise. This is the filter I use when the thread starts repeating itself. Not driving it hard until I know more.
TrailGarage119Community StarterCommunity StarterJun 10, 2026permalink
I'd push back a little: Match starting SOC and battery temp if you're comparing 1993 Mazda RX-7 charge sessions. Then you'll know the next fork. This is from a 1993 Mazda RX-7 in Raleigh with 150,500 miles. A shop burned me once by skipping that step. I already checked the easy fluid levels.
PistonShopperCommunity StarterCommunity StarterJun 11, 2026permalink
I hear you, though I'd still want a second check. On the 1993 Mazda RX-7, I'd get the 12V/DC-DC side checked even if the traction pack looks fine. That's where I'd start. On “7 — old 6v-to-12v conversion has decades,” that was the fork that mattered for me. Write the result down so the next test isn't a repeat of the last one. This is the filter I use when the thread starts repeating itself. Might be overthinking it, but I'd rather overthink than overspend.
ColdStartCamper961Community StarterCommunity StarterJun 10, 2026permalink
That's a good start, but I wouldn't stop there. Try a second charger before blaming the 1993 Mazda RX-7 — site sharing and pack temp change the curve a lot. Then you'll know the next fork. Write the result down so the next test isn't a repeat of the last one. I'm in no rush to be a hero on it.
CanyonMiles650Community StarterCommunity StarterJun 10, 2026permalink
Update: the cheap test changed the symptom, so I'm not throwing parts yet. I'd rather look cautious in this thread than stuck later.
EVRoadie157Community StarterCommunity StarterJun 10, 2026permalink
Charge curves lie if you don't match starting SOC and temp. Match starting SOC and battery temp if you're comparing 1993 Mazda RX-7 charge sessions. I'd do that before spending real money. Time, temperature, and whether it's in gear are the notes that actually help a shop. This is me being the wet blanket on purpose.
TrailGarage119Community StarterCommunity StarterJun 11, 2026permalink
Charge curves lie if you don't match starting SOC and temp. Match starting SOC and battery temp if you're comparing 1993 Mazda RX-7 charge sessions. I'd do that before spending real money. A shop burned me once by skipping that step. Might be overthinking it, but I'd rather overthink than overspend.
WeekendNomadCommunity StarterCommunity StarterJun 11, 2026permalink
I'd treat 12V warnings as a no-ignore. On the 1993 Mazda RX-7, I'd get the 12V/DC-DC side checked even if the traction pack looks fine. That's where I'd start. On “7 — old 6v-to-12v conversion has decades,” that was the fork that mattered for me. This is from a 1993 Mazda RX-7 in Raleigh with 150,500 miles. Post the numbers (or the code) and people can get more specific. This is the filter I use when the thread starts repeating itself. This is me being the wet blanket on purpose.
TrailGarage119Community StarterCommunity StarterJun 11, 2026permalink
Low-voltage gremlins will strand you even with a full pack. Try a second charger before blaming the 1993 Mazda RX-7 — site sharing and pack temp change the curve a lot. I'd do that before spending real money. Learned this the expensive way on a previous car. This is the version I'd tell a friend.
CommuterBuilder83Community StarterCommunity StarterJun 12, 2026permalink
I'd push back a little: Try a second charger before blaming the 1993 Mazda RX-7 — site sharing and pack temp change the curve a lot. Then you'll know the next fork. If they can't show the line item, I assume it's hiding. Worth doing even if the car feels fine right now. Doing the boring step first on purpose.
PistonShopperCommunity StarterCommunity StarterJun 11, 2026permalink
Don't clear the alert just to make the screen pretty. Leave the alerts on the 1993 Mazda RX-7 so service can see what you saw. I'd do that before spending real money. Keep sale price, fees, and rate as three different conversations. This is me being the wet blanket on purpose.
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