volts jumping up and down

[BYSONRYE]

I have a 2005 siverado 5.3. I noticed my volt meter in the truck going up and down. Also at about the same time my transmission started going into limp mode. I went and had the codes read and it said I had a bad transmission solenoid. I had them replaced and my truck is still going into limp mode. The mechanic at the shop said I probably need my transmission rebuilt. I didnt hardly agree with him at all and asked him why my volts where bouncing up and down. He said it was probably my alternator, so I had it tested. The guy at advanced auto parts said the alternator was good but didnt know why the volts were jumping up and down. He asked another guy in the store and he said the magneto might be going bad. So I purchased a new alternator and it was doing the same thing. Put old one back on. Also noticed heat guage jumping up and down, along with my passenger air bag light switching from on to off from time to time as I get in the truck and start it up. I read on the internet that if the transmission is not getting the right amount of volts sent to it , it will cause it to go into limp mode. All these things seem to have started about the time I replaced my battery after it wouldnt charge anymore. I had it tested and they said it was bad so I bought a new battery. It seems since I have had the new battery all these things started happening. I am so confused. I hope someone can understand what I have wrote and help me out.

[BYSONRYE]

ttt

[BYSONRYE]

Anybody got anything for me?

[2000CAYukon]

I recently purchased a 2005 Sierra 5.3 2WD and I have not noticed any issues with my volt meter going up and down.

If things started when a new battery was installed, I would double check the battery connections again.

//2000CAYukon

[j cAT]

Originally Posted by 2000CAYukon

I recently purchased a 2005 Sierra 5.3 2WD and I have not noticed any issues with my volt meter going up and down.

If things started when a new battery was installed, I would double check the battery connections again.

//2000CAYukon

I agree the battery connections are corroded or loose , will throw the tranny into a weird shifting mode . seen that before.


the alternator may be failing. these alternators have a voltage regulator that has a circuit board the gets damaged from corrosion. soon your alternator will totally go and the battery red light will come on.

battery volts should be solid 14volts on dash.

2005 this could be also another issue with your dash indicators that GM had recalls on ! check this out .

it is possible you have a few problems.

[j cAT]

the alternators have defective voltage regulators . they get corroded and fail this way then totally go.

with the voltage jumping this is why the tranny is going weird on shifting.

2005 the limp mode is usually the throttle body TAC.

if the other dash indicators are failing this may be the dash panel is defective another recall item !

[BYSONRYE]

Originally Posted by j cAT

the alternators have defective voltage regulators . they get corroded and fail this way then totally go.

with the voltage jumping this is why the tranny is going weird on shifting.

2005 the limp mode is usually the throttle body TAC.

if the other dash indicators are failing this may be the dash panel is defective another recall item !

Thanks for the reply's. I went and got a new alternator a few days ago and immediately started having the same problems. So I put my alternator back in and returned the new one.
I went home last night and checked to make sure the battery cables were tight. Everything was tight. I decided to go back to Auto Zone and have them test the battery and alternator again. They both checked that they were good, but at the same time the volts were bouncing up and down on their machine. I told him I have not had any of these problems until I put the new battery in 3 weeks ago. He told me that he wasn't suppose to swap out the battery because it was good but he would swap it for me. I think he could see the frustration in my face. He put another battery in it and so far I have not had anymore issues. I got my fingers crossed. I will post in a day or two and let everyone know if my truck is still running fine.

[j cAT]

Originally Posted by BYSONRYE

Thanks for the reply's. I went and got a new alternator a few days ago and immediately started having the same problems. So I put my alternator back in and returned the new one.
I went home last night and checked to make sure the battery cables were tight. Everything was tight. I decided to go back to Auto Zone and have them test the battery and alternator again. They both checked that they were good, but at the same time the volts were bouncing up and down on there machine. I told him I have not had any of these problems until I put the new battery in 3 weeks ago. He told me that he wasn't suppose to swap out the battery because it was good but he would swap it for me. I think he could see the frustration in my face. He put another battery in it and so far I have not had anymore issues. I got my fingers crossed. I will post in a day or two and let everyone know if my truck is still running fine.

I have seen only once where a battery shorted out. this was an exide battery. this will also cause this , since this will not blow any fuses but put a very large load on the alternator causing this drop.

surprised that it was so intermittent.

did they put the load tester on the battery ? with the engine off this should reveal an internal defect of the battery.


what is the battery they installed , want to stay clearof that one.

[BYSONRYE]

They did test the battery under load but with the truck running. It was an everlast battery. A DL-78 I believe. I have been around the world with this whole deal. I have been told I need the transmission rebuilt, transmission solenoids, new alternator, to a new computer. With two of the fixes being pretty expensive, while at the same time being told that it might not fix the problem.

[j cAT]

Originally Posted by BYSONRYE

They did test the battery under load but with the truck running. It was an everlast battery. A DL-78 I believe. I have been around the world with this whole deal. I have been told I need the transmission rebuilt, transmission solenoids, new alternator, to a new computer. With two of the fixes being pretty expensive, while at the same time being told that it might not fix the problem.

I have a everlast on my silverado now its 6yrs old. could be this new batch is bad.

post back on what other issues come up with all these drivability issues.

they messed up on the battery test. with the vehicle OFF , they are to hook up a large battery charger looking device. this is just a load grid that will indicate the batterys capacity to produce AMPS. it has a scale green good , yellow fair . a new battery should be in the good zone and the current should hold steady.

[BYSONRYE]

I have always had good luck with everlast batteries in the past. So far the one that I replaced it with last night seems to have fixed the problem. I got in it today when I went to lunch and it was still running right above 14 volts with no jumping around. Transmission running like a champ as well. Only thing I am worried about now is where I had the solenoids put in I had new transmission fluid put in and filter changed. I have always been told on a vehicle with high mileage it is not a good thing to do. Usually end up having to rebuild transmission because of it. I hope that is not the case for me.

[j cAT]

Originally Posted by BYSONRYE

I have always had good luck with everlast batteries in the past. So far the one that I replaced it with last night seems to have fixed the problem. I got in it today when I went to lunch and it was still running right above 14 volts with no jumping around. Transmission running like a champ as well. Only thing I am worried about now is where I had the solenoids put in I had new transmission fluid put in and filter changed. I have always been told on a vehicle with high mileage it is not a good thing to do. Usually end up having to rebuild transmission because of it. I hope that is not the case for me.

tranny pan drop and fliter replacement is good. don't want to use a flushing machine on the older vehicles because it will loosen and get the particles stuck in the torque converter fouling up the tranny valves etc...

replace fluid / filter every 30,ooomi use the new dexron VI . do not use dexron III.......this is the fluid that GM dropped. cost too much on tranny damage / defective fluid for these trannys.

[BYSONRYE]

UPDATE: Got in my truck last night to go to town and my transmission went back into limp mode. I put it in park, turned the truck off, sit there for a minute, turned it back on and it was fine. Just so happens that a guy that works with me brought me one of those Auto Zone scanners in case I had anymore trouble. I run the codes last night and these are the codes I got. Here is a list of the codes I got in order from 1 to 3. P0740 , P0785 , P2761 My volts are still running where they need to be. Anyone got any advice for me on these codes? Once again I have a 2005 Cheverolet silverado 1500 4 wheel drive.

[j cAT]

Originally Posted by BYSONRYE

UPDATE: Got in my truck last night to go to town and my transmission went back into limp mode. I put it in park, turned the truck off, sit there for a minute, turned it back on and it was fine. Just so happens that a guy that works with me brought me one of those Auto Zone scanners in case I had anymore trouble. I run the codes last night and these are the codes I got. Here is a list of the codes I got in order from 1 to 3. P0740 , P0785 , P2761 My volts are still running where they need to be. Anyone got any advice for me on these codes? Once again I have a 2005 Cheverolet silverado 1500 4 wheel drive.

start a new post with this issue. this will attract more input.

check the wires going to the transmission,connector for security/shorts/chaffing/rodent damage.

did this occur after the transmission servicing ? If so the transmission pan install may have damaged/short out the wiring to the solenoids[very common] the shift braket area you should inspect for damage as when the pan is dropped this shift bracket must be removed it is possible this was bent and things got damaged.

check ignition fuse O . make sure it sets into the fuse socket securely.

possible that the ignition switch contacts feeding this circuit are bad. this can be checked with a meter.

[BYSONRYE]

No this problem was going on before I had the transmission worked on. The problem I am having is why I had the solenoids changed in the first place. The check engine light came on after it went into limp mode. I went and had the codes checked and it showed that the solenoid needed to be changed. So I had it changed.