Truck Starter/solenoid/battery help

My Fluke meter has a bar graph at the bottom to give you some insight to what is going on when the digits aren't clear.

I have a T100 and had the same solenoid contact problem which I repaired. Actually I should be due for them to go bad again, it's on

I don't think you can say which is bad as yet. All you know is there is an intermittent open between the point you are measuring along the path to the battery through ground. But given the known issue with the solenoid, I would suspect the contacts. How many miles since you replaced the contacts or the whole starter?

I think I know a little more than that, the starter is like a 0.05 ohm resistor, so if I had a bad connection chances are the voltage would drop a lot lower than 11.8V with the starter engaged. YMMV

I think so, but I can add a wrinkle, I noted oil dripping from the starter/solenoid, so a new theory is the oil has contaminated the contacts in the solenoid causing intermittent operation. I'm going to hold off until the problem becomes more common or clears itself. I have tighten the very loose bolts holding the valve covers.

I don't know, but we don't put 5,000 a year on the truck, and the starter was replaced within two years. 91k miles now on a 17 year old vehicle, but the previous owner put on more than our 5K per year in 3 years, before we bought it. ( I thinking it had about 40k miles when we got it)

Mikek

If the connection were intermittent it could be completely open and pass no current. That's what you think is happening in the solenoid, no? Starters have brushes... You would only notice a voltage change if the bad connection was between the meter and the battery. A bad ground connection would still read high on your meter.

Isn't the solenoid on top of the starter? Is the oil inside the solenoid?

That makes me think it is not the solenoid unless it really is your oil problem. Mine wore out around 100 kmiles and I recall that was typical.

I got mine a year old with 11 kmiles on the odometer. The only complaint with the original owner is they smoked and I could smell it in the summer when I turned on the AC for maybe three years!

It has held up well, but repairs are *expensive*. The AC seems to be a regular repair item. $1k every 5 or 6 years. Maybe I should get a Chevy unit?

I had this exact, same symptom with my auto, 1972 classic. intermittent start,

never got to measure but discovered that there was a build up of crud between the battery cable and the clamp to the battery cable that caused the whole problem. if not at battery, somewhere else along the path?

Uh, I think you snipped TOO much... I can't tell what you are replying to... lol

Ah, you are replying to my post, but not really to me.

Except that, when the starter fails to run I still have 11.9 volts on the input side of the solenoid, when the starter does run the voltage drops to 10.7 volts. Which I suggest is very close to battery voltage under starter load. I'm fairly confident the problem is the contacts in the solenoid. But as I've said I fixed the oil leak right above the starter/solenoid, and hope to burn off any oil by use. The last 100 starter attempts produce no failures. As I said very intermittent. (or cleared itself he wrote with fingers crossed)

Mikek

I believe I've seen two problems on Toyotas. First was that the stationary contacts that the solenoid bridges got so worn that the solenoid would no longer reliably bridge them. Secondly, I believe I have also seen the brushes in the starter wear down to the point where they no longer made contact with the commutator and again, things stopped working (or maybe that was my compound mitre saw).

I'll put my 2 cents in..

Possible engine ground strap is loose and with all that oil running down the side, the attempts to start is heating up the bad joint and cooking the oil away, then has a semi connection to start, and it may start ok for some time after that. Taking a meter reading from the - side of the battery terminal over to the solenoid will show that you have 12 volts there.

I had this problem years ago in an old ford straight 6 engine.. What flag me to the device giving me the problem was the fact that the alternator light would come on now and then and one day I noticed it would come on when I jumped into the engine, which made the engine move sideways a bit.

The big issue is, if you don't get the oil problem corrected, it can cause an engine fire with all that oil, in the case of arcing.

You could also have loose bolts on the starter!

Jamie

The starter brushes will wear in any vehicle although they usually don't stop making contact, instead the carbon wears away until the metal backing wears down the contacts on the rotor destroying it (much like your brake pads do). But maybe they put in a stop to prevent that.

The solenoid in this model Toyota starter has an issue where the plunger bridges the two contacts, but doesn't balance the pressure. So once one starts to wear more than the other it has less pressure and becomes the point of make/break taking all the wear. At some point the one contact wears away to the point of not working... much sooner than if the bridge across the two contacts was able to float and provide equal pressure at all times. At least that is how I remember it.

That reminds me of something else I saw on my truck. Once the engine became intermittent and stopped on the highway. I lifted the hood (as if there would be something I could "see"...) and wiggled some things. I found a loose ground wire in the area of where the carburetor would have been if it had one, lol. I turned the key and it started. I tightened up the screw by hand and used a wrench when I got back to the house. So ground straps can come loose.

Not if he can't get it to fail...

That *was* years ago if it was a current car at the time. What 60's, early 70's?

thank you for understanding, apologies, that was waaaay too much snip! but in defence my reply was more 'chiming in' than 'replying to'

Forgot to mention the crud build up was NOT between the battery and the cable clamp, but inside the cable itself between the clamp and the rest of the cable!

First time failed, thought was the battery, had battery replaced, worked great for a while, then started failing again. Thought the car's electrical was 'eating' batteries, because everytime a battery replacement, the cable was jostled just enough to make it last another 6 months to a year.

Final solution was to replace the cable, and it actually crumbled apart at the clamp by that time.

starter brushes are wear parts too.

get under there with a jumper and connect the coil terminal to the battery terminal. if that works the problewm is before the solenoid if not measure the voltage on the switched solenoid contact.

high is a bad motor low is a bad solenoid,

if you want to reduce wear and load and improve safety while testing remove the spark plugs.

It could still be a fault in the branch of the battery cable that goes to the starter. often the rest of the electrics are connected to the branch that goes to the altenator.

I don't see it that way. There is a cable directly from the battery to the solenoid. When the starter motor turns the voltage is 10.6v, when it doesn't turn it is 11.8v. If the problem was in the "branch of the battery cable that goes to the starter" then I wouldn't have 11.8v on the solenoid. It has to be after the 11.8v point or else the starter would run on 11.8v. If the problem was a bad connection in the "branch of the battery cable that goes to the starter" the all the voltage would drop across that bad connection. 1ohm 0.05ohm It would be like this series circuit +12v----^^^------^^^----grd The 1 ohm represents the bad connection and would have 11.43v across it, that leaves 0.57 volts across the 0.05 ohm that represents the starter.

It must have worked all day today, no complaints from the wife and she was out with it all day.

Mikek

There are TWO cables to the starter. The other one is from the ground of the battery and goes to some bolt on the engine. If this one is intermittently bad you will see exactly the same symptom as a bad contact unless you can probe the connection between the solenoid and the starter.

I can't remember, can you probe the point between the solenoid and the starter?

I have a problem with my truck now. Something is wrong with the electrics. When I put the headlights on the voltage will drop and after a few minutes the battery warning light comes on. I expect if I didn't turn them off the engine would eventually die. Without the headlights it seems to be able to power everything ok.

That's usually signs of a bad alternator, a shorted diode most likely.

Jamie

I was thinking it was likely the alternator... or the regulator, but I believe they build the regulators *in* the alternator these days, no?

Another symptom is I hear a whine on the radio when I turn on the lights. Sounds to me like one phase of the alternator is not working. I'll have to swap it out. Only $133 for a rebuilt one.

Yes. The whine from the radio is a bad DIODE, common problem.

At night time if you have a GEN light, turn off the dash lights and you should see it on. Maybe. This also, depending on how bad it is, can cause the battery to run down if you don't use the truck often enough.

You can rebuild it yourself if you feel confident. You can get rebuild kits around 50 bucks.

Jamie

Ny neighbor had a Toyota truck that wasn't charging and it was a bad diode. He replaced the diode with one he had picked up somewhere and the alternator worked fine after that for several years until he sold the truck. I have personally rebuilt 4 or 5 alternators. The kits are usually pretty cheap. lots cheaper than a rebuilt. They have always been easy to fix. And even though I have bought rebuilt alternators that I had to take back because they were bad I have never rebuilt one that didn't work perfectly afterward. Eric Eric