Electrical power cutting out while driving
 

Hey guys,
So earlier this year I was experiencing some issues where all the electrical power on my truck would cut out for like a fraction of a second. When it first happened, I ignored it as the truck still drove, then within a span of 15 mins it would happen again my engine would die. The car starts right up again after.

So I carefully drove home, inspected my battery cables, ground connections and checked my fuses but couldn't find anything.

My first thought, battery & alternator going bad. So I changed the battery, tested the alternator and purchased new heavy duty battery terminals from SHD.

After that, truck ran fine. Issue went away. Then 2 months later.. happens again. So this time I change the alternator to a brand new OEM one.

About 2 months later, shit happens again. I do some deep thinking, and I realized that each time I thought I fixed the problem was because I unplugged the battery. So that's what I did. I unplugged the battery and let the ECU reset. Sure enough the truck ran fine again.

So for the past year, every time my power blips, I stop, get out and unplug the negative terminal, wait 10 secs, plug it back in and I'm good for another 2 months or so.

Anyone else run into this issue? Is it the ECU? Should I replace the ECU? Or get it reprogrammed? Is this something the dealer can only do?

Run a diagnostic scan to see if you have any errors. Typically with electrical something will pop up , and not always throw a CEL

Not just your fuses, check the relay. Relays are hard to diagnose because it is the main "current or Amp" pathway. Testers aren't 100% either because it only tells you a connection is made but doesn't tell you "how much" current or "amp draw" it's allowing to pass through.

I had a brand new 21 Taco with an electrical issue dealer couldn't figure out why the truck wouldn't start intermittently. I took it home frustrated and found the blue color fuel pump relay had a slightly off center contact patch and isn't allowing at least 10A through the pathway. Bending the center contact doesn't really fixes it either so I started using the Grey relay (part# 90987-02028) and never had a starting problem again. Grey relay has the same electrical property as the blue but it's sealed. DO NOT use purple relay to replace blue or grey because it uses higher current draw solenoid for starters and not for constant-on purpose.

The way Toyota design their electrical pathway is genius because everything goes through the relay as a way to buffer low current I/O to a higher current I/O, if electrical pathway is overloaded there is the fuse and there is also a relay to prevent the main wire from burning. But the only problem is burnt fuses are easy to find, tired old relay not so easy to test.

To me, relays are cheap (relative to alternator and battery), I would replace all critical path relays after 10 years. IG-1 (computer module 1), IG-2 (computer module 2), EFI-1, EFI-2 (fuel pump), INJ (fuel injector), A/F HTR (Air Fuel oxygen sensor heater).

I had this happen the other day.

Lose all electrical power for a second or so, then power back. Enough to reset my radio.

Happened 5 or so times until I pulled over. Turned the truck off, restarted, and hasn't happened since.

No clue on what caused it, was assuming ECM glitch or something as I still had ignition.

Cleaning the ground points might help. Dirty or corroded ground points do some weird things.

Very true. I've had really weird things, like instruments going crazy with bad grounds.

Any update on this? I am having the same issue, while vehicle is parked or driving using any additional electronics causes all electronics to shut off/reset.

While driving for example if I put my high beams on, the vehicle will sputter, all interior and headlights will turn off for one second before coming right back on.

Battery Voltage is 12.56 while car is off and 13.80 while car is on.

Have no issues start up. Issue also happens intermittently. Have checked cables and connections both seem fine.

I had this happen on another vehicle. It was an intermittent problem so it took a few trips to the dealer to convince them that there was a problem. Finally I convinced the service advisor to take the truck and drive it for a couple of weeks. When it happened to him he brought in a specialist to go over the electrical system with a fine toothed comb. It turned out to be a loose connector on the main harness. The connector was properly re-seated and the problem never happened again. Hope that helps.

Before you go swapping out the ECU, think about checking for error codes first. A diagnostic scan can clue you in on what's causing those power blips. Also, take a look at the ignition switch—it might be the culprit. A wonky ignition switch can mess with the electrical flow and cause those blips. Keep an eye out for any patterns when it happens, like turning the key or jiggling the ignition switch. If there's a link, it could be worth checking or swapping out the ignition switch.