Diagnosing no crank

[Malleus]

 

[CJF]

Nice wet and stormy day for some driveway fixin. Anywho after reading 12.6V, I decided to remove the battery cables and reinstall my trickle charger leads just in case I'd need them. I brushed the terminals, reconnected everything, and gave it a crank - it works.

What's your voltage reading across the battery while the engine's running?

 

[jatree]

View attachment 3793194

Thanks! I was able to test EA and EB (both 0 Ohms) but couldn't locate EC. Will try again today.

What's your voltage reading across the battery while the engine's running?

14.6V

If the battery cable is loose you won't get a good charge from the alternator or the full current needed for cranking the engine over. The is the major clue we were missing.

My guess is that when you replaced the battery the connection felt snug but was never fully tight (causing high resistance). Temperature, vibration and other variables caused some of the intermittent issues you were seeing since the connection to the battery was never that great.

I think you're right. My quick check wasn't thorough and when I came back is when I realized I could move it by hand. I also tightened down the battery hold down and a tear in the tray has me looking for improvements.

I was able to get a load test at Interstate and the battery checked out fine. The only way to check an alternator is bench test right? The 14.6V while running makes me think it is working but I don't know how a "degrading" alternator behaves if that's even a thing.

 

[Malleus]

If your lights are/were flickering, there is a very good chance you voltage regulator is dying. You can replace it with an aftermanrket regulator, they're about $40, but they won't last more than a year (two if you're very lucky). The OEM regulator is more than the alternator, from the dealer. Dave Stedman at Japan4x4 can get them cheaper, but you have to wait for the trip from the land of the rising sun.

Auto parts stores may have an alternator tester. Napa doesn't anymore; try Advance or AutoZone. You can try the troubleshooting steps in the service manual, but they won't tell you what's wrong, just that it fails the test.

FWIW, the spin testers at the parts stores may have a diagnostic, but you'll have to find someone there who knows how to use the tester to get anything from it.

 

[Malleus]

Thanks! I was able to test EA and EB (both 0 Ohms) but couldn't locate EC. Will try again today.

14.6V


I think you're right. My quick check wasn't thorough and when I came back is when I realized I could move it by hand. I also tightened down the battery hold down and a tear in the tray has me looking for improvements.

I was able to get a load test at Interstate and the battery checked out fine. The only way to check an alternator is bench test right? The 14.6V while running makes me think it is working but I don't know how a "degrading" alternator behaves if that's even a thing.

EC is at the back of the driver's side of the engine. Follow the wire; you'll see it.

 

[jpw2]

14.6 running is good charging voltage, often testing in the vehicle is actually more accurate than bench testing.

Turn on high beams, AC on high blower, rear defrost, hazards, wipers and hold the brake down while monitoring battery voltage at idle and at 1500 RPM is a true loaded Dynamic test.

If you're near 13 or better at idle and 13.5 or better at 1500 the alternator is doing good enough to maintain your battery with normal loads (winch, compressor, big stereo is another conversation) unless your use is just short trips (stiil work but battery life is usually shorter).

Checking the diodes is a little bit more complicated (for later if needed).

if your battery was 12.6 while you were having the problem and it load tested good logic says it had been getting charged just fine up until then.

Advice on checking / cleaning connections is always good.

Familiarizing yourself with the circuits Malleus posted is good practice especially if you end up having this problem repeat in an intermittent manner (quite common as our vehicles age). Especially since the starter circuit is one of the simpler circuits on your vehicle.

Unfortunately ohm testing does not take into account load, many times poor connections that prevent full voltage / current getting though a circuit to a component will ohm test perfect.

Testing for voltages with ignition 2 pin connector or EFI main fuse unplugged (prevents engine from firing to allow longer test time) and cranking the engine is a true loaded true test (keep the trickle charger on between tests, have a helper to turn key). Taking the time to do it while it's working will show you what you should have so that when it's not working you have a comparison.

Park neutral switch is a fairly common cause of difficult to find no crank problems, of course it's not the easiest thing to get to. Using some t-pins slid into the connector while still connected alongside the wire can help you test it live (CAREFUL NOT TO GOUND YOUR TEST PINS, makes sparks and blows fuses ).

I crudely marked up Malleus diagram, dark blue is positive voltage from fusible link at B+ to energize the starter solenoid through all connections and the park neutral safety switch, red is starter battery cable stud to the starter case, light blue is your test pins ( patience, imagination and eyeballs on the end of your fingers help get them in position as testing needs to be done with everything connected).

 

[Mark W]

Your initial symptoms screamed bad battery contact. Your end result (starter now works after cleaning and tightening the terminals) says "yep, bad battery contact".

You found it and fixed it.

Battery terminals and clamp surfaces can suffer from oxidation and even burning as well as corrosion.

Mark...

 

[jatree]

14.6 running is good charging voltage, often testing in the vehicle is actually more accurate than bench testing.

Turn on high beams, AC on high blower, rear defrost, hazards, wipers and hold the brake down while monitoring battery voltage at idle and at 1500 RPM is a true loaded Dynamic test.

If you're near 13 or better at idle and 13.5 or better at 1500 the alternator is doing good enough to maintain your battery with normal loads (winch, compressor, big stereo is another conversation) unless your use is just short trips (stiil work but battery life is usually shorter).

Checking the diodes is a little bit more complicated (for later if needed).

if your battery was 12.6 while you were having the problem and it load tested good logic says it had been getting charged just fine up until then.

Advice on checking / cleaning connections is always good.

Familiarizing yourself with the circuits Malleus posted ...

This is super helpful info. Your bolded statement is what gave me some confidence that charging wasn't involved but I'll still perform the more comprehensive load test - thank you.

I always assumed the battery gauge was as "fuzzy" as the temperature gauge but since I've been staring at it for the last week, I now notice that the turn signal indicators cause the battery needle to tick a bit. It's rock steady when I turn all other accessories on but will test properly with a multimeter. The indicator ticking seems to be a common issue on the forum.

I appreciate the image markup - saving that - and great point on testing while working to be prepared for later. While I'm back up and running now, I kind of have it in the back of my mind to go ahead and replace the alternator as part of the work I want to do ahead of 200k miles.

 

[Malleus]

It sucks that the voltage regulator is so expensive, since that (and the brushes) are typically the failure modes for an alternator. Otherwise, you could just replace the voltage regulator.