Not starting/

Tiny
AUBREY BUBBA SOMMER
  • MEMBER
  • 1974 DODGE TRUCK
  • 5.2L
  • V8
  • 2WD
  • AUTOMATIC
  • 180,000 MILES
The truck listed above is a D100. I went out to my truck on Thanksgiving to start it and all I got was a small stutter on the first crank from my starter and just a click on the second. Today I went and swapped out the starter thinking that it had a flat spot in it and the same issue. After that swapped out the starter solenoid and same issue. I was able to use a screwdriver to jump the starter and get the truck going but that’s the only way so far. I’m thinking by working down the line the next step would be ignition switch. Any ideas?
Saturday, November 25th, 2023 AT 4:05 PM

3 Replies

Tiny
CARADIODOC
  • MECHANIC
  • 33,743 POSTS
Hold on. You're jumping around and now you're headed to the ignition switch, a part that produces a response when turned.

Would it be possible for you to upload a video that includes the sounds you hear under the hood when a helper turns the ignition switch to "crank"? If not, you'll have to describe the sounds. To start with, can you hear the light click of the starter relay? OR, do you hear one fairly loud clunk from the starter solenoid? That's built onto the starter motor, so you have a different one there now since you replaced the starter.

We also have to consider a run-down battery and corroded battery cables. Do you have a digital voltmeter and know how to use it? If not, I can help on both accounts.
You can also turn on the head lights, then observe how bright they are, and what happens to their brightness when you try to crank the engine.

Let me know as much as possible, then we'll figure out where to go next.

Also follow the battery's negative cable and be sure the fatter one is bolted to the engine block, not to the body sheet metal. The smaller negative wire does go to the body. Be sure that one is tight and not rusty.
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Saturday, November 25th, 2023 AT 4:55 PM
Tiny
AUBREY BUBBA SOMMER
  • MEMBER
  • 2 POSTS
I apologize. The starter would make a few clicks like the battery was on a very low charge. I would turn off the truck and then try again. On the second try there would be no sound. I checked the battery, and it is holding a charge. After the battery is when I swapped out the starter for a new one and after putting the starter same thing. A couple clicks on the first attempt and then no noise on the second. When I swapped out the starter relay the motor turned over and I had thought that was the end of it. I turned off the truck and attempted to start again. I got the same clicks and then nothing. Thank you for any help. Electrical is not my strong suit.
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Sunday, November 26th, 2023 AT 9:14 AM
Tiny
CARADIODOC
  • MECHANIC
  • 33,743 POSTS
Dandy. The place to start is by measuring the battery's voltage. If you don't have a digital voltmeter, you can find a perfectly fine one at Harbor Freight Tools for $7.00. Also look at Walmart or any hardware store. This article:

https://www.2carpros.com/articles/how-to-use-a-voltmeter

is useful if you don't know how to use the meter. Be aware they're using an "auto-ranging" meter. That is an expensive feature you don't need. If you need help setting up your meter or with reading it, I can help with that.

First, with the engine and everything else off, the battery should measure 12.6 volts. If it is closer to 12.2 volts, it's good but fully discharged. When it's that low, the head lights can still be bright, but it won't be able to run the starter motor. Charge it at a slow rate with a portable battery charger for a few hours. If the engine cranks normally then, and the engine starts, you may have a charging system problem that isn't recharging the battery. Regardless, when the engine is running, measure the battery voltage again. Now it must be between 13.75 and 14.75 volts. If it stays near 12.6 volts, we have to diagnose the charging system.

If you find the battery is at 12.6 volts, turn on the head lights and observe their brightness. Now try to crank the engine. Tell me if the brightness of the lights doesn't change, if they dim just barely a noticeable amount, or if they go almost completely out.

This next step is going to involve a helper. You'll need to measure the voltage down on the starter's larger terminal. For the most accurate results, the meter's red positive probe should be touching the copper stud where the fat battery cable is bolted on. Most people touch the probe to the copper terminal on the end of the cable. That leaves out one connection in this test, so it's much preferable to touch the tip of the stud / bolt instead. You're going to find the same voltage that you just had right at the battery. Hopefully that will be 12.6 volts. What's important is what that voltage drops to when your helper turns the ignition switch to "crank". The shaking can make it difficult to keep the probe in place. To address that, I use a small jumper wire to connect the probe to the stud. You can find a pack of ten of them at Harbor Freight Tools too for about $4.00.

When the starter system is working normally, the very high current being drawn is going to pull the battery's voltage down a little. The industry standard is to no lower than 9.6 volts. That's what you're watching for on this test, but you're doing it at the far end of the battery cable instead of right at the battery. This way we're testing all the connections too. Tell me what that voltage drops to during cranking. Also tell me if during that test the starter cranks the engine or if you just hear that clicking again.

So far I haven't mentioned the meter's black negative probe. Some of my meters have a spring-loaded "alligator" clip so it can be attached and ignored. When the negative lead is a probe like the red one, I also use one of those small jumper wires. That probe or jumper wire can be attached to the battery's negative cable, any paint-free point on the engine, or any paint and rust-free point on the body sheet metal. When it reaches, I prefer using the battery's negative cable. However, if you find in the previous test the voltage stays up well above 9.6 volts, move the negative meter probe to a spot right on the engine, then do the test again. This way we're including the battery's negative cable in the test. During cranking, now you're reading the exact voltage the starter motor is seeing, which is the most accurate value for diagnosis. If it comes to that, tell me what you find. Remember that value. Next, go back to the battery and measure the voltage right there and see what it drops to when your helper tries to crank the engine. Ideally both readings should be very nearly the same. If the voltage at the battery remains well above 9.6 volts but down by the starter it drops a real lot lower, there is a bad connection we have to find. That is actually rather easy, but it takes some time to describe.

Let me know what you find up to this point.
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Sunday, November 26th, 2023 AT 4:23 PM

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