Starter ground issue? Engine block ground?

[JaceL]

I have a 2002 TJ 4.0 manual that is having issues turning over. I have already replaced the battery and starter multiple time and have had both tested since. I have also gone through the starter wiring issue form (https://wranglertjforum.com/threads/jeep-wrangler-tj-wont-start-read-this.1201/). My issues starts when i place my ground from the battery to the block. If battery ground and wiring harness ground are connected but NOT attached to the block I don't get a voltage drop. As soon as I attach the ground to the block I get a voltage drop. I have taken a wire brush to the block and cleaned up the contact and it hasn't helped. Starter solenoid is either engaging or flickering, but not turning. I thought the engine might of some how seized so i tried bump starting it and it cranked and was close to starting but didn't start. Any ideas on where I would be getting a voltage drop on the block?

 

[Chris]

I have a 2002 TJ 4.0 manual that is having issues turning over. I have already replaced the battery and starter multiple time and have had both tested since. I have also gone through the starter wiring issue form (https://wranglertjforum.com/threads/jeep-wrangler-tj-wont-start-read-this.1201/). My issues starts when i place my ground from the battery to the block. If battery ground and wiring harness ground are connected but NOT attached to the block I don't get a voltage drop. As soon as I attach the ground to the block I get a voltage drop. I have taken a wire brush to the block and cleaned up the contact and it hasn't helped. Starter solenoid is either engaging or flickering, but not turning. I thought the engine might of some how seized so i tried bump starting it and it cranked and was close to starting but didn't start. Any ideas on where I would be getting a voltage drop on the block?

Here are a few things to consider:

Make sure that all ground connections are clean and tight, not just at the battery and engine block but also where the ground wires connect to the chassis. Sometimes a poor or corroded connection elsewhere can cause issues.

Use a multimeter to check the continuity of your ground connection from the battery to the block. There should be minimal resistance (close to 0 ohms). If you see significant resistance, that indicates a poor connection somewhere.

Sometimes, the area where the ground cable attaches to the engine block can be problematic, even after cleaning. You might want to try a different location on the block or use a star washer to help create a better contact or even add an additional grounding strap from the engine to the chassis.

Inspect the wiring around the starter, including the solenoid and any associated connectors for any signs of wear or shorts that could be affecting the voltage when attempting to start.

Since the solenoid is engaging or flickering, it may be beneficial to check the starter relay and associated fuses for any signs of being blown or malfunctioning.

If you’re still having issues, consider checking the neutral safety switch (on manual transmissions it could be a clutch safety switch). Sometimes, these can prevent the starter from engaging properly.

Perform a voltage drop test on the starter circuit to see if there's excessive drop occurring somewhere other than just the ground connection.

Given that you've already cleaned the block, don't hesitate to try some of the suggestions above, especially considering cleaning other ground points and verifying all connections. Good luck, and keep us posted on what you find!

 

[NDSpeed]

i’ve started replacing the grounding straps on my jeep. just as a precautionary step. i hate chasing wires

 

[NskLJ]

I have a 2002 TJ 4.0 manual that is having issues turning over. I have already replaced the battery and starter multiple time and have had both tested since. I have also gone through the starter wiring issue form (https://wranglertjforum.com/threads/jeep-wrangler-tj-wont-start-read-this.1201/). My issues starts when i place my ground from the battery to the block. If battery ground and wiring harness ground are connected but NOT attached to the block I don't get a voltage drop. As soon as I attach the ground to the block I get a voltage drop. I have taken a wire brush to the block and cleaned up the contact and it hasn't helped. Starter solenoid is either engaging or flickering, but not turning. I thought the engine might of some how seized so i tried bump starting it and it cranked and was close to starting but didn't start. Any ideas on where I would be getting a voltage drop on the block?

To properly test this hook up the ground cable where it should be. Take a voltmeter and connect the positive lead to the negative terminal at the battery then take the voltmeter negative lead and attach it to the negative cable connection at the block. Try to crank it over, read the voltage on the meter. This will show the voltage loss in the negative cable. If it’s over .5 volts replace the cable . Repeat for positive cable.

 

[B1Toad]

Have you ruled out your negative cable by temporarily connecting a jumper cable between your battery - and the block?

 

[JoseA]

might be time to do the jeepcables big 7 upgrade

 

[KennethS]

If you’re still having issues, consider checking the neutral safety switch (on manual transmissions it could be a clutch safety switch). Sometimes, these can prevent the starter from engaging properly.

With the manual transmission, the switch can be bypassed by inserting a fuse in the TRANS slot.

 

[macleanflood]

Short to ground - more specifically the engine block on the engine harness and most likely something in the ASD circuit.

I'd trace out and ohm test the little wire to the starter first.

Wiring diagrams are in the resources section - Factory Service Manuals.

-Mac

 

[Link]

Do you have a test light and a volt meter?

 

[B1Toad]

As soon as I attach the ground to the block I get a voltage drop.

OK going to need some clarification here. Are you saying you get a voltage drop to the starter when you connect the negative to the block and try cranking, or are you saying battery voltage drops when you connect the negative to the block before you even try the starter or any other loads?

 

[JaceL]

OK going to need some clarification here. Are you saying you get a voltage drop to the starter when you connect the negative to the block and try cranking, or are you saying battery voltage drops when you connect the negative to the block before you even try the starter or any other loads?

For clarification I have a voltage drop at crank when the ground is connected to the block. It drops to around 6v. When the ground isn’t connected to the block but is connected to the wiring harness ground I do not get a voltage drop at crank.

 

[JaceL]

Do you have a test light and a volt meter?

Yes I do have a test light and a multimeter

 

[g.hayduke]

For clarification I have a voltage drop at crank when the ground is connected to the block. It drops to around 6v. When the ground isn’t connected to the block but is connected to the wiring harness ground I do not get a voltage drop at crank.

More clarification needed. Please describe your exact scenario with details. Where are you measuring exactly and what are the readings under what conditions? Need to eliminate mucho ambiguity in this discussion.

 

[Lou]

With the manual transmission, the switch can be bypassed by inserting a fuse in the TRANS slot.

That was an AI response.

 

[topfuel83]

For clarification I have a voltage drop at crank when the ground is connected to the block. It drops to around 6v. When the ground isn’t connected to the block but is connected to the wiring harness ground I do not get a voltage drop at crank.

This sounds normal to me. The starter is grounded through the engine block, therefore return current flows back through the engine block. If you take the ground off the engine block and try to engage the starter, nothing will happen as they is no return path to the battery. Your voltage drop is from a large starter load when trying to engage the starter. Are you sure you have the correct starter, it's installed correctly, and the starter gear isn't bound up on something?

And I wouldn't rule out multiple bad starters. I've seen it before in bad batches. You could always bench test the starter or have an auto parts store test it.

 

[macleanflood]

Nothing will happen as they is no return path to the battery.

Unless you have something in the engine harness shorted to ground...then it would try and ground through that small gauge wire and possibly/probably through the PCM.

I agree you probably have a bad starter or heavily corroded battery and ground cables.

If you have some large gauge jumper cables you could try using those temporarily to see if the starter runs better.

-Mac

 

[KennethS]

That was an AI response.

Yeah, I figured. It read like it.

 

[Link]

Forget all this talk about voltage drop. It’s not really relevant at the moment and confusing everyone. When the battery is connected and you try to start it, does it crank over? I’m guessing not but need that explained.

Connect the battery directly to the starter. Use jumper cables. Use a small wire to connect the positive to the solenoid. Does the starter spin/engine crank over? Or, take the starter out. Connect it to a good battery. Does it spin over?

Sounds possibly like a bad starter but you have to test it.

 

[NskLJ]

Forget all this talk about voltage drop. It’s not really relevant at the moment and confusing everyone. When the battery is connected and you try to start it, does it crank over? I’m guessing not but need that explained.

Connect the battery directly to the starter. Use jumper cables. Use a small wire to connect the positive to the solenoid. Does the starter spin/engine crank over? Or, take the starter out. Connect it to a good battery. Does it spin over?

Sounds possibly like a bad starter but you have to test it.

I outlined the proper procedure in post #4 and was waiting for a response to proceed with testing.

 

[Stockli]

Have you checked the connectors on your pos and neg bat cables? I had a similar issue. Mine was intermittent but it all came down to a bad connection with the negative battery connector. There was some corrosion in the factory connector (molded) and it was causing continuity issues. Changed it out and never had an issue again. Sometimes they look ok but the connection is crap.