Could some one tell me where to find a schematic or diagram for the engine starting circuit. The truck is a 2007.5 LMM.
I got something weird going on. Thanks
I got something weird going on. Thanks
Bill T
If it does not crank----
First check the batteries-- probably need new ones if original-
Ground the TCM, common for guys to spark the fins and that burns the small ground wire in the TCM. Results no crank.
First check the batteries-- probably need new ones if original-
Ground the TCM, common for guys to spark the fins and that burns the small ground wire in the TCM. Results no crank.
OK I will try to explain what's going on. The batteries, Interstate Megatron Plus, CCA 730, are less than two years old. This has happened twice, first time was in Jan. 2015, second time right now. I hope I can explain this so you will understand. I am a poor explainer. lol
1- truck sat for four days, attempted to start it, all I got was a heavy clunk, engine did not turn over, hmmm I said, batteries are dead
2- got the Fluke out and checked battery voltages, left battery 12.4 vdc, right battery 12.6 vdc, why don't they read the same, parallel circuit aren't they?
3- remember I've been thru this once before
4- connected the meter to the right side battery, attempted to start, all I got was a heavy clunk, but the battery voltage did NOT drop as you would expect if there was a heavy load applied, the voltage stayed at 12.6 vdc
5-connected the meter to the left side battery, tried to start, voltage dropped to 9.5 vdc, is this battery dead? continuing on
6- disconnected left side battery, truck started on the one right side battery
7-reconnect the left side battery, disconnect the right side battery, truck stared on the one left side battery
8- reconnect the right side battery, both batteries connected, truck starts as usual. What happened? All I touched was the one battery post on each battery.
9- all the battery post are very clean, crawled under the truck to check the ground connections on the engine, not easy for a 71 year old man, but they were clean. Solenoid terminal was clean and tight. Any thoughts or suggestions from those of you who did not fall asleep before the end. lol
1- truck sat for four days, attempted to start it, all I got was a heavy clunk, engine did not turn over, hmmm I said, batteries are dead
2- got the Fluke out and checked battery voltages, left battery 12.4 vdc, right battery 12.6 vdc, why don't they read the same, parallel circuit aren't they?
3- remember I've been thru this once before
4- connected the meter to the right side battery, attempted to start, all I got was a heavy clunk, but the battery voltage did NOT drop as you would expect if there was a heavy load applied, the voltage stayed at 12.6 vdc
5-connected the meter to the left side battery, tried to start, voltage dropped to 9.5 vdc, is this battery dead? continuing on
6- disconnected left side battery, truck started on the one right side battery
7-reconnect the left side battery, disconnect the right side battery, truck stared on the one left side battery
8- reconnect the right side battery, both batteries connected, truck starts as usual. What happened? All I touched was the one battery post on each battery.
9- all the battery post are very clean, crawled under the truck to check the ground connections on the engine, not easy for a 71 year old man, but they were clean. Solenoid terminal was clean and tight. Any thoughts or suggestions from those of you who did not fall asleep before the end. lol
OK I will try to explain what's going on. The batteries, Interstate Megatron Plus, CCA 730, are less than two years old. This has happened twice, first time was in Jan. 2015, second time right now. I hope I can explain this so you will understand. I am a poor explainer. lol
1- truck sat for four days, attempted to start it, all I got was a heavy clunk, engine did not turn over, hmmm I said, batteries are dead
2- got the Fluke out and checked battery voltages, left battery 12.4 vdc, right battery 12.6 vdc, why don't they read the same, parallel circuit aren't they?
where did you check the voltages from? did you use the positive and ground on each battery? and were the batteries still hooked into the system? they need to be unhooked because while hooked up you should have a reading that is that same....that being said the difference of .2volts if both batteries are hooked into the system concerns me. I would suspect bad positive or ground for on of the batteries and when you unhooked the batteries it "fixed" the problem until next time in loses connection.
3- remember I've been thru this once before
4- connected the meter to the right side battery, attempted to start, all I got was a heavy clunk, but the battery voltage did NOT drop as you would expect if there was a heavy load applied, the voltage stayed at 12.6 vdc
5-connected the meter to the left side battery, tried to start, voltage dropped to 9.5 vdc, is this battery dead? continuing on. the voltage is close to the bad side normally on a load test in it goes below 9.5 its bad, and your right at it, now this was the battery with the low volts so would have to charge and retest to know but its something to look at, and one bad battery will kill a good one. it seems at at this point only the left battery was connected but now you have move cables and the problem may have temp fix itself by you moving cable.
6- disconnected left side battery, truck started on the one right side battery
7-reconnect the left side battery, disconnect the right side battery, truck stared on the one left side battery
8- reconnect the right side battery, both batteries connected, truck starts as usual. What happened? All I touched was the one battery post on each battery.
9- all the battery post are very clean, crawled under the truck to check the ground connections on the engine, not easy for a 71 year old man, but they were clean. Solenoid terminal was clean and tight. Any thoughts or suggestions from those of you who did not fall asleep before the end. lol
I have a question is this a classic body that still has side post batteries of the new style with top post batteries. if its top post I believe that they have a junction on one of the positive posts with some fuses and cable splitting off. I would check all the positive connections and ensure they are tight.
1- truck sat for four days, attempted to start it, all I got was a heavy clunk, engine did not turn over, hmmm I said, batteries are dead
2- got the Fluke out and checked battery voltages, left battery 12.4 vdc, right battery 12.6 vdc, why don't they read the same, parallel circuit aren't they?
where did you check the voltages from? did you use the positive and ground on each battery? and were the batteries still hooked into the system? they need to be unhooked because while hooked up you should have a reading that is that same....that being said the difference of .2volts if both batteries are hooked into the system concerns me. I would suspect bad positive or ground for on of the batteries and when you unhooked the batteries it "fixed" the problem until next time in loses connection.
3- remember I've been thru this once before
4- connected the meter to the right side battery, attempted to start, all I got was a heavy clunk, but the battery voltage did NOT drop as you would expect if there was a heavy load applied, the voltage stayed at 12.6 vdc
5-connected the meter to the left side battery, tried to start, voltage dropped to 9.5 vdc, is this battery dead? continuing on. the voltage is close to the bad side normally on a load test in it goes below 9.5 its bad, and your right at it, now this was the battery with the low volts so would have to charge and retest to know but its something to look at, and one bad battery will kill a good one. it seems at at this point only the left battery was connected but now you have move cables and the problem may have temp fix itself by you moving cable.
6- disconnected left side battery, truck started on the one right side battery
7-reconnect the left side battery, disconnect the right side battery, truck stared on the one left side battery
8- reconnect the right side battery, both batteries connected, truck starts as usual. What happened? All I touched was the one battery post on each battery.
9- all the battery post are very clean, crawled under the truck to check the ground connections on the engine, not easy for a 71 year old man, but they were clean. Solenoid terminal was clean and tight. Any thoughts or suggestions from those of you who did not fall asleep before the end. lol
I have a question is this a classic body that still has side post batteries of the new style with top post batteries. if its top post I believe that they have a junction on one of the positive posts with some fuses and cable splitting off. I would check all the positive connections and ensure they are tight.
Confirmed Fix Details
Tech Reported Fix Details
Confirmed Fix
1 TROUTWINE1
September 12, 2013
2008 Chevrolet Silverado 3500 HD, LTZ 6.6L, V8, Diesel, Asp T, VIN 6, Des LMM, 32V, USA *
Battery Ground Cable
- Measured voltage drop on cables. important to remove starter relay fuse to get a extended crank of 5-10 seconds. Use a min max meter and record voltage drops. Anything over .250 volts is bad. Found worst spot at .864 volts at connection of RH battery negative post connector and cable crimp.
Repaired Battery Ground Cable
2 DJAutomotive3
August 12, 2013
2010 Chevrolet Silverado 3500 HD, LT 6.6L, V8, Diesel, Asp T, VIN 6, Des LMM, 32V, USA *
Battery Ground Cable
- Battery Ground Cable
Replaced Battery Ground Cable
3 Tech
January 8, 2013
2008 Chevrolet Silverado 2500 HD, Wt 6.6L, V8, Diesel, Asp T, VIN 6, Des LMM, 32V, USA *
Battery Ground Cable
121,327 miles Replaced Battery Ground Cable
1 Jason Stein
December 5, 2013
2008 Chevrolet Silverado 2500 HD, LT 6.6L, V8, Diesel, Asp T, VIN 6, Des LMM, 32V, USA *
Both Batteries
- replaced both batteries,failed when tested
Replaced Both Batteries
1 David Maze
January 7, 2014
2009 Chevrolet Silverado 2500 HD, LTZ 6.6L, V8, Diesel, Asp T, VIN 6, Des LMM, 32V, USA *
Engine Block Ground(s)
- bad grond
Repaired Engine Block Ground(s)
I searched a site and seems there are a lot of problems with loose/bad grounds even at the actual crimp at the battery cable. and a few problems on the positive cable side. deff a bad conncetion and when you move the cables it resolves itself until it vibrates loose. check all connections and do the wiggle test wiggle things trying to get it to act up again. if nothing is found ohm all the grounds. there is a TSB out about some fuses loose in the underhood panel check and make sure they are all tight.
Tech Reported Fix Details
Confirmed Fix
1 TROUTWINE1
September 12, 2013
2008 Chevrolet Silverado 3500 HD, LTZ 6.6L, V8, Diesel, Asp T, VIN 6, Des LMM, 32V, USA *
Battery Ground Cable
- Measured voltage drop on cables. important to remove starter relay fuse to get a extended crank of 5-10 seconds. Use a min max meter and record voltage drops. Anything over .250 volts is bad. Found worst spot at .864 volts at connection of RH battery negative post connector and cable crimp.
Repaired Battery Ground Cable
2 DJAutomotive3
August 12, 2013
2010 Chevrolet Silverado 3500 HD, LT 6.6L, V8, Diesel, Asp T, VIN 6, Des LMM, 32V, USA *
Battery Ground Cable
- Battery Ground Cable
Replaced Battery Ground Cable
3 Tech
January 8, 2013
2008 Chevrolet Silverado 2500 HD, Wt 6.6L, V8, Diesel, Asp T, VIN 6, Des LMM, 32V, USA *
Battery Ground Cable
121,327 miles Replaced Battery Ground Cable
1 Jason Stein
December 5, 2013
2008 Chevrolet Silverado 2500 HD, LT 6.6L, V8, Diesel, Asp T, VIN 6, Des LMM, 32V, USA *
Both Batteries
- replaced both batteries,failed when tested
Replaced Both Batteries
1 David Maze
January 7, 2014
2009 Chevrolet Silverado 2500 HD, LTZ 6.6L, V8, Diesel, Asp T, VIN 6, Des LMM, 32V, USA *
Engine Block Ground(s)
- bad grond
Repaired Engine Block Ground(s)
I searched a site and seems there are a lot of problems with loose/bad grounds even at the actual crimp at the battery cable. and a few problems on the positive cable side. deff a bad conncetion and when you move the cables it resolves itself until it vibrates loose. check all connections and do the wiggle test wiggle things trying to get it to act up again. if nothing is found ohm all the grounds. there is a TSB out about some fuses loose in the underhood panel check and make sure they are all tight.
chevy hd thanks for your time and help.
On my #2 - voltage readings were taken with both batteries connected, meter probes were on the battery post not the connectors. the .2vdc differential was a concern to me.
#5 - I first suspected a bad battery, but in step 7 that battery by itself did start the truck.
Question - the truck is a new body style, 2007.5, top post on the batteries, aprox. 61,000 miles.
The fuses you mentioned. Are they the 3 heavy ones on the right side, mounted on the firewall near the right side battery?
In January when this problem first started I had Advance Auto check the batteries and their tester showed they were good. I later went to the old alternator / generator rebuild shop and had them tested again on their old style battery checker. They checked good there but was told that since they were sealed batteries there could still be an electrolyte issue.
So I will start cleaning cable connections and then take it from there.
Thanks again.
On my #2 - voltage readings were taken with both batteries connected, meter probes were on the battery post not the connectors. the .2vdc differential was a concern to me.
#5 - I first suspected a bad battery, but in step 7 that battery by itself did start the truck.
Question - the truck is a new body style, 2007.5, top post on the batteries, aprox. 61,000 miles.
The fuses you mentioned. Are they the 3 heavy ones on the right side, mounted on the firewall near the right side battery?
In January when this problem first started I had Advance Auto check the batteries and their tester showed they were good. I later went to the old alternator / generator rebuild shop and had them tested again on their old style battery checker. They checked good there but was told that since they were sealed batteries there could still be an electrolyte issue.
So I will start cleaning cable connections and then take it from there.
Thanks again.
your welcome, I enjoy this stuff that's why I do what I do. and I love dmaxs so I glad to help when I can. the .2volt difference could shown up due to one battery being isolated(the one with highter voltage would be out of the circuit.) and then the one with lower voltage is the one being used so it would have the lower voltage. check the cable where it hooks into the battery terminal strap the crimp could be bad, or a small crack in the clamp that is having a on off connection. if I could figure out how to show a pdf file on here id load it but I cant figure that out. but, it didn't specify what one just fuses it the fuse panel, the plug in kind, the terminal that holds the fuse gets loose, from testing, or people putting a wire in the terminal to add a circuit. so it cause temp problems with starting,. im not to familiar with the three fuses your talking about but heck check everything for looseness and clean. im convinced there is a bad wire or something electrical related to the batteries, but it seems that the batteries are ok, if one was bad they usually are bad all the time not every six months or so they act up haha. if I can help anymore let me know or if you find something interested in hearing the fix. have a good night.
same issue
I had the same issue. would only start on the driver side battery and only charge the driver side. when I unhooked the battery leads on both and hook them back up it would start fine for a few weeks to a month. Fought in for a year. I ended up soldiering new terminals on the passenger side battery cables and ran a new ground wire to the engine block. Starting fine no issues for over 2 months. the only thing is after I did that, I get a electrical whine in the cab that varies in pitch with the rpms.
I had the same issue. would only start on the driver side battery and only charge the driver side. when I unhooked the battery leads on both and hook them back up it would start fine for a few weeks to a month. Fought in for a year. I ended up soldiering new terminals on the passenger side battery cables and ran a new ground wire to the engine block. Starting fine no issues for over 2 months. the only thing is after I did that, I get a electrical whine in the cab that varies in pitch with the rpms.
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
