It's Back! Over Charging Problem 68 Dodge Truck
#2407334
11/22/17 01:17 PM
11/22/17 01:17 PM
|
Joined: Jul 2007
Posts: 2,554 Maryland
wally426ci
OP
master
|
OP
master
Joined: Jul 2007
Posts: 2,554
Maryland
|
Ok, I've been reading heavily everywhere to diagnose this.
Truck cranks forever & sputters when letting off the key. For the last 6 months it was starting often when letting off the key. I've read about voltage drop through firewall plug and bad ignition switches. I've improved the problem by either replacing or fiddling with ECU harness (converted to Mopar electronic ignition). That fix doesn't last long and it happens again.
I have a Volt meter in place of AMP gauge inside the truck and it is now reading at 10- while idling and getting close to 12 with rev. Previously, it was 11.5 @ idle and almost 14 with rev.
I know there are a lot of variables, but is there a diagram somewhere that shows me acceptable voltage readings to the corresponding point under the hood? I know there is expected drop for each component but trying to figure out what readings I "should" be getting.....
Thank you in advance!
Last edited by wally426ci; 01/04/21 09:59 AM.
|
|
|
Re: Finding the Voltage drop 68 Dodge Truck issue
[Re: wally426ci]
#2407346
11/22/17 01:43 PM
11/22/17 01:43 PM
|
Joined: Sep 2007
Posts: 14,889 up yours
Supercuda
About to go away
|
About to go away
Joined: Sep 2007
Posts: 14,889
up yours
|
In order to know your voltage drop you have to know what is coming out of hte alternator.
10V at idle with 12V revved up is BAD.
11.5v at idle with 14 revved is also bad.
Since we have no idea where you voltmeter is actually tied into the system it's hard to say what it's reading. If you simply bolted the two ammeter connections together and used that point as the freed for the voltmeter then you should be reading alternator out put and if it's that low you have serious issues.
We may as well start at the beginning ...
What is the reading at the battery positive - (use engine block for ground)
engine off - engine at idle - engine at 2500 rpm -
What is the reading at the alternator stud - (use engine block for ground)
engine off - engine at idle - engine at 2500 rpm -
What is the reading at the coil positive - (use engine block for ground)
engine off - engine at idle - engine at 2500 rpm -
Once we have these we can go from there
They say there are no such thing as a stupid question. They say there is always the exception that proves the rule. Don't be the exception.
|
|
|
Re: Finding the Voltage drop 68 Dodge Truck issue
[Re: 469runner]
#2407349
11/22/17 01:44 PM
11/22/17 01:44 PM
|
Joined: Sep 2007
Posts: 14,889 up yours
Supercuda
About to go away
|
About to go away
Joined: Sep 2007
Posts: 14,889
up yours
|
Check your Ballast resister. Ignore this. The ballast resistor will NOT have any affect on system voltage, which is very low. Nor is it used in START. It is bypassed with the key in START and the fact that it will sometimes start when the key is released shows it is good.
They say there are no such thing as a stupid question. They say there is always the exception that proves the rule. Don't be the exception.
|
|
|
Re: Finding the Voltage drop 68 Dodge Truck issue
[Re: wally426ci]
#2407516
11/22/17 07:04 PM
11/22/17 07:04 PM
|
Joined: Nov 2003
Posts: 36,041 Lincoln Nebraska
RapidRobert
Circle Track
|
Circle Track
Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
|
Truck cranks forever & sputters when letting off the key. I've improved the problem by either replacing or fiddling with ECU harness (converted to Mopar electronic ignition). 4 pin orange box I am assuming. I would jump 12V from the battery positive post to the blue yellow ECU terminal and to the coil positive primary terminal & seperately (on the ground side) from the ECU base to ground then crank it & see if it starts several times in a row & only let it run for several seconds if/when it does start to confirm or elim the coil/ECU are good tho they can be OK when cold then act up when hot but you did say this was an initial in the morning starting problem. then as said check voltage drops at the coil/ECU when cranking OR just start cleaning ALL terminals/connections especially the bulkhead & ign sw.
live every 24 hour block of time like it's your last day on earth
|
|
|
Re: Finding the Voltage drop 68 Dodge Truck issue
[Re: wally426ci]
#2407700
11/23/17 02:36 AM
11/23/17 02:36 AM
|
Joined: Nov 2003
Posts: 36,041 Lincoln Nebraska
RapidRobert
Circle Track
|
Circle Track
Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
|
Thank you for the kind words & I could use a vacation but the thought of the airport delays would probably make me want to stay put. for the charging rate I would confirm that the battery is full charged by slo charging it with a charger to full charged then put it on a fast idle & see what you get at the alt & at the batt terminals. I'm wondering if this is a charging rate or a voltage drop (connections/terminals) or a part (coil/ECU/switch) issue. The battery could be sulphated (least likely) but a possible potential. We're getting there.
live every 24 hour block of time like it's your last day on earth
|
|
|
Re: Finding the Voltage drop 68 Dodge Truck issue
[Re: RapidRobert]
#2407705
11/23/17 02:52 AM
11/23/17 02:52 AM
|
Joined: Nov 2007
Posts: 21,909 Kirkland, Washington
Pacnorthcuda
Too Many Posts
|
Too Many Posts
Joined: Nov 2007
Posts: 21,909
Kirkland, Washington
|
Truck cranks forever & sputters when letting off the key. I've improved the problem by either replacing or fiddling with ECU harness (converted to Mopar electronic ignition). 4 pin orange box I am assuming. I would jump 12V from the battery positive post to the blue yellow ECU terminal and to the coil positive primary terminal & seperately (on the ground side) from the ECU base to ground then crank it & see if it starts several times in a row & only let it run for several seconds if/when it does start to confirm or elim the coil/ECU are good tho they can be OK when cold then act up when hot but you did say this was an initial in the morning starting problem. then as said check voltage drops at the coil/ECU when cranking OR just start cleaning ALL terminals/connections especially the bulkhead & ign sw. Wally, As FastBob states above, check your bulkhead connections. Your comment "sputters when letting of the key" is a classic indicator that the STARTING circuit to the ignition has failed. Not uncommon.
|
|
|
Re: Finding the Voltage drop 68 Dodge Truck issue
[Re: wally426ci]
#2408735
11/25/17 05:42 PM
11/25/17 05:42 PM
|
Joined: Sep 2007
Posts: 14,889 up yours
Supercuda
About to go away
|
About to go away
Joined: Sep 2007
Posts: 14,889
up yours
|
As Andrew said, 15.5 is probably too high, your idle is too low. Your coil voltages look ok and where you have checked I do not see a voltage drop issue. I would say voltage drop to the voltage regulator on the sense side needs looked at, usually it's a blue wire but it is the switched 12V feed to the VR. Measure that to engine block and it should be the same as the battery + terminal or alternator output stud voltages, if not you have an issue if so it's probably the regulator. In 68 you should still have the single field terminal alternator with the mechanical regulator system, unless it has been changed. If you are still running the mechanical voltage regulator instead of the later electronic version of it (not to be confused with the 70 and up regulator) you can adjust turn on and turn off voltages. To tell if it's the mechanical regulator look at the bottom, if it has a couple wire wound resistors it's the mechanical one. The FSM has adjusting procedures in it. No truck FSM's, but the 68/69 pass car ones have the relevant info in them http://www.mymopar.com/index.php?pid=109I would think about converting to the newer charging system http://www.mymopar.com/index.php?pid=78
They say there are no such thing as a stupid question. They say there is always the exception that proves the rule. Don't be the exception.
|
|
|
Re: Finding the Voltage drop 68 Dodge Truck issue
[Re: wally426ci]
#2408747
11/25/17 06:53 PM
11/25/17 06:53 PM
|
Joined: Jul 2007
Posts: 2,554 Maryland
wally426ci
OP
master
|
OP
master
Joined: Jul 2007
Posts: 2,554
Maryland
|
I have not probed the regulator points. I did swap the regulator for no change. I then decided to swap another alternator in. That changed the volt ratings inside the truck and it now pulses by a half an amp or so.. See my youtube upload https://youtu.be/6DkWHOLzsxk
|
|
|
Re: Finding the Voltage drop 68 Dodge Truck issue
[Re: wally426ci]
#2408748
11/25/17 06:57 PM
11/25/17 06:57 PM
|
Joined: Sep 2007
Posts: 14,889 up yours
Supercuda
About to go away
|
About to go away
Joined: Sep 2007
Posts: 14,889
up yours
|
that is what a mechanical regulator looks like when it's doing it's thing.
They say there are no such thing as a stupid question. They say there is always the exception that proves the rule. Don't be the exception.
|
|
|
Re: Finding the Voltage drop 68 Dodge Truck issue
[Re: wally426ci]
#2408800
11/25/17 09:24 PM
11/25/17 09:24 PM
|
Joined: Sep 2007
Posts: 14,889 up yours
Supercuda
About to go away
|
About to go away
Joined: Sep 2007
Posts: 14,889
up yours
|
If you have the newer setup and it's doing that you have a problem.
They say there are no such thing as a stupid question. They say there is always the exception that proves the rule. Don't be the exception.
|
|
|
|
|