Low voltage

Hello can anyone tell me about voltage issues. I just had my alternator replaced and a new battery installed, but my voltage at idle is around 11volts,when I gas on it it jumps up to 14 but drops back down when It goes back to idle.Also my idle is around 400rpm

 

What are you testing the voltage with?

 

Haven't tested it just going by my gauge on the dash. It was doing the same thing before I had alternator replaced also put in a new battery and a new belt

 

It wouldn't hurt to get a volt meter (you can get a "7-Function Digital Multimeter" Harbor Freight for <$5). 400RPM when in drive? My 2008 drops down to about 500RPM in drive and it sits at roughly 700RPM in neutral. Just for kicks, you could check the serpentine belt routing to make sure it wasn't put on wrong when they replaced the alternator.

 

There are lots of very cheap (from $7.00-$12.00) battery and alternators testers you can use. I multimeter, at told above by others, will be fine too. I have a couple of expensive or Pro multimeters, and also the "tester for idiots like me" below. It does all the work for me, and I carry it in a toll bag on long drives, just in case:

$18 Beatifufu 1Pc Automotive Battery and Alternator Tester Professional Car Tool with Led Display for Accurate Battery System Analysis Light Grey

https://www.amazon.com/Beatifufu-Ba...attery+and+alternator+testers,aps,304&sr=8-47

There are cheaper ones that do the same, and you may be able to find then at your local automobile parts stores. But your engine's 5,000 RPM (idle) seems to be on the low side. I would think that it should be around 6,000 or a tad higher (?)

 

Usually sits between 6 to 7 for rpm big issue is was doing the same thing before I had it replaced.

 

Also check for voltage drop between battery positive and alternator positive. Should be virtually none. Check for loose connections, etc.

 

Will check that replaced my terminals as well

 

Good advice about checking all the connection points. And now that you brought that up, I would check the cables near the terminals to make sure they are free of corrosion and tightness, to include the grounding point of the ground cable. After figuring why the low idle RPM, I assume that the alternator is working fine. More than likely the problem is related to the low engine RPM.

 

My truck has gone back to running like normal now showing 14 on my dash Guage n idle is at 650when warmed up. I was told that probably my ecm had to relearn itself. I've put 200 miles on it In the last 2 days n no issues.

 

I have had a starting problem in the past. I believe there is an aftermarket remote starter on the truck,it would not start n start up on its own.I had to remove the fuse from that under the dash.Whan I bought the truck the dealership installed a low jack for the finance company and they patched into the power wire for that remote starter.I do believe that's where my troubles all started from

 

Is the new alternator Denso? Our trucks don’t like Chinesium parts.

 

I'm not sure I bought it at Napa and had toyota dealership install it