My Losi 1/8 Xcelorin seems to have crapped out on me, but I need to know how to diagnose it as the issue...

I was running my Ofna buggy last week, all was good, esc temps never above 120. All of a sudden, it just died... No smoke, no smell, nothing, just doesn't work any more.

Batteries are good. It's definitely plugged in, etc... I've checked all the basic stuff. Now I need to know what the next step would be in diagnosing a bad esc? Anyone know which direction to lead me?

Thanks!

I'd check the switch. I've had alot of them go bad and you can test it by cutting it off and twisting the wires together. Also check your solder connections at both ends of the power leads.

If that doesn't bring it to life then I think she's done

Hmmm, I was just about to try that, but the on/off switch has three wires (like a servo). It's got the program button built into it, to calibrate the radio to the esc. That said, I don't think cutting it off is an option, is it?

not positive on the excelorin but the white wire is usually the signal wire on esc's. You could cut the other two (power and ground) and try twisting them together. Got nothing to lose if its out of warranty.

Three wires on the power switch because you ground red to turn it on, and ground WHITE to press the SET button.

I've had switches quit working in two Novaks and one Tekin. Its worth a shot

OK, so I would remove the on/of switch, and tie red/brown (neg) to keep the esc "ON." Leaving the white wire loose?

Then, if I need to enter program mode, I'd disconnect the red from the brown, and touch the white to the brown which is essentially pressing the "set" button? Does that sound right?

Tying red to black will turn the ESC on, yeah.

Touching white to black will do the same thing as pressing "Set".

So yep, you've got it right.

One easy diagnostic is to check the BEC function. They occasionally go bad, then no power to the radio and steering servo. So only worth a shot if you don’t have steering.

Try a receiver battery (normally not good practice on a working ESC without pulling the red wire, but if it’s dead anyway…). If it works you can either run a Rx battery or an external BEC, cheaper than a new ESC.

Yeah, there's nothing going on at all. With the battery plugged in, the Rx doesn't turn on, no steering, nada. She's got no juice.

So you say if I plug in an external Rx pack, it may bring it all back to life assuming the ESC's internal BAC function is pooched. OK, I'll try that out! Thanks for the tip!

Only if the transistors for the linear BEC aren't totally blown out. If they are, it's still salvageable, but requires some specific electronics knowledge to go any further.

So troubleshooting steps would be:

1) Try an external Rx pack to attempt to remedy faulty BEC.

If that doesn't work...

2) Remove on/off switch, and hard-wire to permanent "on" position.

If neither of those work, send 'er on back to Losi for service. Sound about right?

Certainly worth trying, in addition to the switch already discussed. Something I’ve always done as a diagnostic, doesn’t always work of course, but it’s helped more than a few guys out, myself once.

My best friends Savage has been ran like this for a couple years if not longer. It completely died, the BEC transistor had definitely let out the Magic Smoke. I quickly tried an old Rx 4 cell AA holder, kicked right off. He later picked up a Novak HV BEC, still running fine.

I once got an apparently dead Tekin 411P through a big race day by hotwiring the main battery directly in. Fortunately the servo survived! Turned out it had only lost ground and was easily fixed, still works without the hotwire.

Good luck!