Chasing a possible grounding problem in my 2005 500..In my previous posting with slow starting and rough idle issues when cold, I replaced 165K starter with a new unit. Installed it and still turned over slower than it should. It did start but ran poorly for the first few minutes then smoothed out and was ok..Advice here was too use jumper cable from battery ground to starter housing and try starting when cold. Did that and it started right up and ran perfectly. So I’m guessing a ground issue from battery to engine block.

On the wiring diagram I see a G107 ground location down there somewhere near the starter. . Does anyone know specifically where it is. I really don’t want to remove the starter in a search saga if someone knows where the G107 location is.

As a follow up to OP. I did replace the plugs, coils, EGR/ESM module (due to a MAP code.). Also replaced a weak starter that was pulling a high current on the bench test.
Please help!

 

Ground Distribution (Electrical) index page shown above.
Ground Point (Location) index page shown below.



G107 check 151-3 above, or below here:

 

Not all folks are up to speed working with electrical diagrams, so maybe we can make this a little easier.

All vehicle batteries have a positive post/terminal connection shown with a + sign and a negative post/connection shown with a - ,minus sign.
The negative terminal is usually called the ground side/connection.
All vehicles have a large diameter cable coming from each post of the battery to certain parts of the vehicle. These cables and their connections are subject to corrosion resulting in poor connections. The cables can also be corroded inside the vinyl covering, which if that is the case requires replacement.
A lot of vehicles will have a large cable coming from the negative post of the battery connected to the vehicle engine and also a smaller size wire providing a ground supply to the sheet metal/body of the vehicle..All connection locations are subject to corrosion over time.They may look clean and tight, but still have corrosion under the connection, so they should be checked and cleaned when we suspect a possible grounding problem. Some vehicles also may have a braided cable coming from the engine to the chassis of the vehicle. All this is "usually" located in the engine compartment. Please don't hesitate to ask for assistance if you need any help..

A last word of caution, never allow any metal tools to touch the positive and negative terminals at the same time.It will cause sparks and generate a lot of heat !
When contemplating doing any work with battery cables/wiring always remove the negative battery cable first and connect that battery cable last.

 

Tried starting again this morning. Had ground cable from battery to starter to override any grounding problems. Turned over but not as quickly as it should, and did start but ran poorly as before Sounds like running on 3 cylinders and almost stalled. After poor running for a couple minutes it smoothes out and all is well. So basically nothing has changed except the new starter is working. No codes on scanner after warmed up and smooth running.

Back to square one as in initial posting.

 

You mention a scanner. What kind of info can it provide ?

The post explaining how it started right up with a jumper cable connected as an aux grd is causing some confusion. Do you have any other test equip to use, if so we can guide you through a few voltage drop tests to eliminate some possibilities. Just like a doctor looks at your blood work a good tech can look at data stream info and explain a lot..Low voltage can be a possibility, as can a fuel system problem .The idea is to examine the parameters and see what is or is not happening.

 

It started up one time and ran smoothly with a ground jumper cable connected when cold..Subsequent cold starts even with ground jumper produced the same slower cranking and rough starts. It sounds like it’s missing badly, engine is shuddering until it warms up and then runs smoothly..
My scanner is Harbor Freight Maddox MR14 ..I’m just learning how to use it so not sure how detailed info it will give me. But once engine is running smoothly, no codes are shown

I have other stuff like voltmeters, etc My confusion is that likeI said at the beginning is on a cold engine, it turns slower than it does when warm, AND when it does start, it shakes like it has a multiple misfires. During this period it won’t rev up using the gas pedal. Two minutes later it smoothes out and runs good.

Trying to figure out why it cranks slower and poorly when cold, especially with a new battery and starter. When warm it cranks faster and run good.

 

We can do a voltage drop test of the battery positive cable.

So far you have provided an alternate path for the ground side, but that was only half the job, the other half is the positive side, which if corroded and offering unneeded resistance thereby providing insufficient power to the vehicle until the alt adds to make up that loss engine runs poorly.

Here is how you can prove that.
Key on, what is the voltage at the battery, should be at least 12.4 volts. Now connect your voltmeter positive (RED) probe to battery positive terminal and negative (BLACK) meter probe to positive battery cable end AT THE STARTER and then go to start the engine. Now that positive cable will be under load and if you see a voltage reading over POINT (.5 volts,)that cable is corroded internally and requires replacement.

 

On a 2027 brand new car and the battery is fully charged, a normal cranking voltage should be 9.6V to 11V.
On an old car with new starter and new battery that cranking voltage range shouldn't change much. As you can tell the age of the cables matter a little, but it's how much current draw (could be 200+ amp) it takes to start a car.
I already mentioned a dozen times, must buy the battery monitor, problem solved as far as starting is concern.

 

How does the battery monitor or the charging system know when to lower the charging rate?

Resistance gets into the picture. If there is resistance where the monitor connects to the battery the charge rate dro0ps down to 1 or 2 amps so it doesn't cook the battery and if there is corrosion offering resistance because it thinks the battery is fully charged, guess what !

 

I've got a cranking voltage of 9.84V this morning. If I recall my last 100 cranks are as follows:
10 between 9.0V to 9.3V
10 between 9.31V to 9.6V
60 between 9.61 to 9.99V
20 between 10V to 10.5V

9.6V is the minimum healthy cranking voltage, which would show green on the battery monitor, any voltage under 9.6V would show in red color.
So 80% of the time my cranking voltages are above 9.6V which is considered healthy of course on my 98 E150 4.2L.

Imagine if I consistently getting red color (below 9.6V) 50/100 of the times, that is a good sign of a problem to the starting system, which includes battery, starter and its wiring.
saemetric specifically stated that he got a new battery and new starter, so it can be bad battery cables, of course assuming his new battery is in good condition, and not a low SoC (below 50%), if he gets 9.6V or below cranking voltage 5/10 times then it's a good indication of the bad cables.

The battery monitor is a must buy for anyone who drives, I mentioned this a dozen times. It shows more than just the current voltage, the SoC percentage (with history view), and the cranking voltage, and charging test too if you look at the pic shown above.