lights flickering
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Elder User
Joined: Dec 2000
Posts: 808
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lights flickering
Hi all.
Got in my 6.0 the other day and noticed while idling the headlights and interior lights pulsing/flickering. Only at idle. Alt volts good at 14.8 to 15. on a cold start. 11.5 to 12.3 while cranking. Once GP are off and cruising down the HWY. Volts settle in at 13.9 to 14.3.
Going to do some checking this weekend but wanted a little insight before I got started.
Thx
Got in my 6.0 the other day and noticed while idling the headlights and interior lights pulsing/flickering. Only at idle. Alt volts good at 14.8 to 15. on a cold start. 11.5 to 12.3 while cranking. Once GP are off and cruising down the HWY. Volts settle in at 13.9 to 14.3.
Going to do some checking this weekend but wanted a little insight before I got started.
Thx
Postmaster
Joined: Aug 2015
Posts: 3,910
Likes: 18
From: NW IA
Bad spot in the alternator? Might not show up on a reading since it's too quick to affect the readout. Check all the obvious grounds too.
Might have to bench test it to rule it out. The higher the RPM's the less pronounced it will be.
Might have to bench test it to rule it out. The higher the RPM's the less pronounced it will be.
Thread Starter
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Elder User
Joined: Dec 2000
Posts: 808
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Yes, that's what I'm thinking. Going to check all my battery connections and add that extra negative ground to the driver's side frame to block. Positive to alternator cable while I'm at it too.
Postmaster
Joined: Jan 2005
Posts: 4,424
Likes: 12
From: BC Canada
How old is this 6g to 3G alternator conversion and how hard has it had to work? Can you get the alternator tested and I am talking measured voltage and amps at idle, 2000 and 3000 RPM. Also if you can check for AC ripple current or send for bench testing? I am assuming all your grounds and cables are good, I think it's possible it's just a loose connection so make sure all is clean and tight. I am not familiar with your exact 6 to 3G alternator, I think knowing what it is supposed to do to spec versus what it is doing would be good to check.
Thread Starter
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Elder User
Joined: Dec 2000
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How old is this 6g to 3G alternator conversion and how hard has it had to work? Can you get the alternator tested and I am talking measured voltage and amps at idle, 2000 and 3000 RPM. Also if you can check for AC ripple current or send for bench testing? I am assuming all your grounds and cables are good, I think it's possible it's just a loose connection so make sure all is clean and tight. I am not familiar with your exact 6 to 3G alternator, I think knowing what it is supposed to do to spec versus what it is doing would be good to check.
Checked cables today. No corrosion found up top. All tight. Going to spend time under the truck this weekend. Clean my grounds and install 1/O additional ground from DS frame to block. I think I'll switch batteries around while I'm at it. They say we should do that once a year anyway. My batteries are 2 years old 1030 CCA East Penn types. Might have them checked anyway.
I'll hopefully find out more this weekend.
Thx for all the replies.
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Elder User
Joined: Dec 2000
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Update: went through and check grounds under truck. Everything good and tight. No corrosion. Checked positive cables. All good
Checked alt output. 14.2, 14.6 at scan gauge. No accessories on. Turned lights on. High beam, AC, radio, wipers, and heated seats. 14.2-14.5 at scan gauge. 15.36 at both batteries. Both batteries read the same. Thought this was too high and thinking voltage regulator is going bad. Went and exchanged alt. It's a ultimate select from O'reillys. 130 amp from a 7.3. They gave me a new one.
Re-did test above. 14.2-14.4 at SG. No accessories on. 14.75 at both batteries with everything on.
All lights still flickering. Thinking it might be unsafe to drive. Might fry something?
Wondering if it's a relay or fuse? Taking both batteries out and having them tested tomorrow.
I am pulling the FICM and having Ed go through it tomorrow.
Any other ideas?
Thx
Checked alt output. 14.2, 14.6 at scan gauge. No accessories on. Turned lights on. High beam, AC, radio, wipers, and heated seats. 14.2-14.5 at scan gauge. 15.36 at both batteries. Both batteries read the same. Thought this was too high and thinking voltage regulator is going bad. Went and exchanged alt. It's a ultimate select from O'reillys. 130 amp from a 7.3. They gave me a new one.
Re-did test above. 14.2-14.4 at SG. No accessories on. 14.75 at both batteries with everything on.
All lights still flickering. Thinking it might be unsafe to drive. Might fry something?
Wondering if it's a relay or fuse? Taking both batteries out and having them tested tomorrow.
I am pulling the FICM and having Ed go through it tomorrow.
Any other ideas?
Thx
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Postmaster
Joined: Aug 2015
Posts: 3,910
Likes: 18
From: NW IA
Don't think you will fry anything if this is just an "at idle problem", perhaps after testing the batteries might shed some light on things.
I think I recall a few years back one of the 6.0's at the farm had a glow plug controller that was not totally unlatching........might be a stretch but can't hurt to swap it around with another one. I read of someone else with the same issue, not saying it is the case here, might have been one of the 7.3's for all I remember.
Does it do the same thing if you unhook the alternator with the mill running? Give it a shot.
Check the batteries on AC volts setting and see what you have with it running, just for the sake of curiosity
I think I recall a few years back one of the 6.0's at the farm had a glow plug controller that was not totally unlatching........might be a stretch but can't hurt to swap it around with another one. I read of someone else with the same issue, not saying it is the case here, might have been one of the 7.3's for all I remember.
Does it do the same thing if you unhook the alternator with the mill running? Give it a shot.
Check the batteries on AC volts setting and see what you have with it running, just for the sake of curiosity
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Former Vendor
Joined: Feb 2010
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Update: went through and check grounds under truck. Everything good and tight. No corrosion. Checked positive cables. All good
Checked alt output. 14.2, 14.6 at scan gauge. No accessories on. Turned lights on. High beam, AC, radio, wipers, and heated seats. 14.2-14.5 at scan gauge. 15.36 at both batteries. Both batteries read the same. Thought this was too high and thinking voltage regulator is going bad. Went and exchanged alt. It's a ultimate select from O'reillys. 130 amp from a 7.3. They gave me a new one.
Re-did test above. 14.2-14.4 at SG. No accessories on. 14.75 at both batteries with everything on.
All lights still flickering. Thinking it might be unsafe to drive. Might fry something?
Wondering if it's a relay or fuse? Taking both batteries out and having them tested tomorrow.
I am pulling the FICM and having Ed go through it tomorrow.
Any other ideas?
Thx
Checked alt output. 14.2, 14.6 at scan gauge. No accessories on. Turned lights on. High beam, AC, radio, wipers, and heated seats. 14.2-14.5 at scan gauge. 15.36 at both batteries. Both batteries read the same. Thought this was too high and thinking voltage regulator is going bad. Went and exchanged alt. It's a ultimate select from O'reillys. 130 amp from a 7.3. They gave me a new one.
Re-did test above. 14.2-14.4 at SG. No accessories on. 14.75 at both batteries with everything on.
All lights still flickering. Thinking it might be unsafe to drive. Might fry something?
Wondering if it's a relay or fuse? Taking both batteries out and having them tested tomorrow.
I am pulling the FICM and having Ed go through it tomorrow.
Any other ideas?
Thx
Thanks for the business on the FICM!
Thread Starter
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Elder User
Joined: Dec 2000
Posts: 808
Likes: 3
Got my extra negative cable today for DS frame rail to block. Decided to freshen up all grounds while waiting on FICM return. Batteries has been disconnected from truck 2 days now. Checked them with my voltmeter. Both batteries had a reading of 12.77. Took them both to where I bought them to have them load tested. He had a hand held electronic reader. DS tested at 831 CA. PS tested at 886 CA. Not sure of the type of load testing done. He said both batteries are good. Going to do some research and check out the proper way of load testing a battery.
Thx for the reply and I can't wait to get my FICM back!!
Added note. Lights pulse also while driving too.
Thread Starter
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Elder User
Joined: Dec 2000
Posts: 808
Likes: 3
Don't think you will fry anything if this is just an "at idle problem", perhaps after testing the batteries might shed some light on things.
I think I recall a few years back one of the 6.0's at the farm had a glow plug controller that was not totally unlatching........might be a stretch but can't hurt to swap it around with another one. I read of someone else with the same issue, not saying it is the case here, might have been one of the 7.3's for all I remember.
Does it do the same thing if you unhook the alternator with the mill running? Give it a shot.
Check the batteries on AC volts setting and see what you have with it running, just for the sake of curiosity
I think I recall a few years back one of the 6.0's at the farm had a glow plug controller that was not totally unlatching........might be a stretch but can't hurt to swap it around with another one. I read of someone else with the same issue, not saying it is the case here, might have been one of the 7.3's for all I remember.
Does it do the same thing if you unhook the alternator with the mill running? Give it a shot.
Check the batteries on AC volts setting and see what you have with it running, just for the sake of curiosity
Going to check this out also.
Former Vendor
Joined: Feb 2010
Posts: 1,803
Likes: 4
Well I did not. Maybe I'll take the alt back and have it bench tested. Is there a charge relay somewhere that could cause this also. Sent you my FICM Yesterday. You should have it tomorrow.
Got my extra negative cable today for DS frame rail to block. Decided to freshen up all grounds while waiting on FICM return. Batteries has been disconnected from truck 2 days now. Checked them with my voltmeter. Both batteries had a reading of 12.77. Took them both to where I bought them to have them load tested. He had a hand held electronic reader. DS tested at 831 CA. PS tested at 886 CA. Not sure of the type of load testing done. He said both batteries are good. Going to do some research and check out the proper way of load testing a battery.
Thx for the reply and I can't wait to get my FICM back!!
Added note. Lights pulse also while driving too.
When you re-install the batteries, go ahead and swap them between spots.
Hotshot
Joined: Dec 2014
Posts: 17,823
Likes: 3,101
From: Jersey Shore
I'd agree with what Ed stated.
The voltages you stated vary too high. V reg issue or poor internal connection. If the glow plug module was at issue you would see voltage dropping then rise to a ceiling of 14.2 -14.4. At over 15v you're in the area of electrolysis, where the hydrogen and oxygen off gasses become explosive, so you want to watch it doesn't stay high for long.
It wasn't covered under the 18 month warranty.
At least with dual batteries you'd have matching sides.
The voltages you stated vary too high. V reg issue or poor internal connection. If the glow plug module was at issue you would see voltage dropping then rise to a ceiling of 14.2 -14.4. At over 15v you're in the area of electrolysis, where the hydrogen and oxygen off gasses become explosive, so you want to watch it doesn't stay high for long.
It wasn't covered under the 18 month warranty.
At least with dual batteries you'd have matching sides.
Thread Starter
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Elder User
Joined: Dec 2000
Posts: 808
Likes: 3
The voltages you stated vary too high. V reg issue or poor internal connection. If the glow plug module was at issue you would see voltage dropping then rise to a ceiling of 14.2 -14.4. At over 15v you're in the area of electrolysis, where the hydrogen and oxygen off gasses become explosive.
It wasn't covered under the 18 month warranty.
At least with dual batteries you'd have matching sides.
It wasn't covered under the 18 month warranty.
At least with dual batteries you'd have matching sides.
I'll be taking the alternator back off and having it tested. Watched your video on current draw and cable install on DS block to frame. I'm doing that mod plus taking all the grounds off and cleaning them.
Spoke with a buddy of mine at the dealer. He said to check headlight, tail light sockets for corrsion and the light switch. He had seen that particular issue cause the same symptoms.
My FICM should be here Wednesday from Ed. I should have everything ready to go by then.
I'll post my results once I have them.
Thx