My alternator is a cheap Carquest "Tough one" ... (Advance Auto house brand). I've had two... first one lasted 12K and this one has lasted around 35K.

Was about 50 miles from home earlier today idling in some heavy traffic when my check gauges chime went off. Took me a minute to realize that the battery/alt gauge was reading zero. Battery is pretty decent, so I turn off everything I could and drove it home. Windows were rolling up slowly, so I could tell it was all battery. Made it home and the CEL had turned on... p0335 and p0340 (crankshaft sensor codes). A few hours later, I started up the car and the freaking thing is charging fine again, however the charging needle was just slightly below halfway point. Usually it's dead center.

Didn't know a failing alt could trip codes for crank sensor... I guess running on battery alone could mess with the engine rotation speed? Anyone ever seen that happen?

Anyone ever rebuilt one of the OEM 136 Amp alternators? Got a used junkyard one in the shed.

 

The battery was low, which is what was causing the sensors to act up. If the computer isn't getting its full 12VDC, then it's not sending the sensors the correct voltages, and isn't reading them properly. Non-issue here, will be fixed when the power is fixed. The main issue is the alternator is dying. If you want to take a whack at it yourself you'll want to replace the regulator and the bearings. I just take them to a local rebuild shop because you get what the parts store should be selling for about the same price, plus the money goes into the pocket of one of your neighbors rather than a giant parts store chain that just replaces what is failed inside only to make the claim that it's completely rebuilt. Yes, they may have replaced a single bearing, but that doesn't mean that the 100K miles on the other bearing and the rectifier will be reliable.

 

Thx. Yeah, I've always wanted to rebuild one myself. Trouble I'm having is finding a genuine Denso rebuild kit.

 

So I cleared the codes yesterday and this evening, I charged the battery and drove the truck about ten miles. The charging issue has not returned. I have a junkyard alternator in a box behind my seat and a few tools, just in case.

Hey, anybody know if a there is a date code on these Denso Alternators? Trying to figure out when it was manufactured.

 

No date code to my knowledge.

https://www.maniacelectricmotors.com...bearings1.html

Looks like TN121000-4540 had a limited lifespan of 2001-2006.

 

I appreciate the info.

I've been driving the truck and the issue has not returned since it disappeared the day after. I put a charger on the battery to get it back up to full, just to take the strain off the alternator. I'm wondering if the alternator is actually failing or if something else is amiss, such as glitch in the PCM, cause the battery gauge went straight to zero and stayed there on the day it happened. Now it's as if it never happened. Now I know I should just replace the alt to eliminate that angle, but I'm wanting to see what happens. Although... I'm thinking it will return at the worst possible time. LOL

 

Took the lazy approach this weekend and threw in the used Denso alternator (no rebuild). Seems to be okay so far. I did pull it from a wrecked Dak, so I know it was doing it's job at that point. The old one was no longer acting up and voltages were within working range, but I didn't trust it anymore (although I'm not even sure the issue was the alternator). Here are the voltages taken with a multimeter...

Old alternator
Engine off (cold) = 12.82 V
Running (cold start) = 13.95 V
Running AC, lights on = 13.95V

"New" Used Denso
Engine off (cold) = 13 V
Running (cold start) = 14.6 V
Running AC, lights on = 14.35 V

Also threw on some rear pads....which is why I didn't feel like fussing with the alternator for too long. Getting old is a b*tch. Sitting in a the wheel well of a truck for a long time left me feeling like I went a few rounds with Mike Tyson.