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Unread 09-25-2011, 07:22 PM   #1
rahijada
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Lights Flashing While Idling

I have a problem I'm trying to figure out, I'm not 100% sure of the details here, but it's what I've observed so far.

To start with...I have a 1974 CJ5 with the 232 I-6. It's pretty stock under the hood, specifically I'm using the Motorola 37 amp alternator, Motorola Voltage Regulator, and a new battery (a few months old).

I just got the Jeep back on the road a few months ago and it's been doing well, but it started cranking slow, then one day it wouldn't start, would just click. Popped the clutch to start it and drove it home.

I tested the battery voltage and was getting just around 12 Volts, but when I'd try and start it all it would do is the clicking. If I hook up jumper cables to my car, I could start it. I charged the battery a week ago and it tested at about 13.5 Volts. I've been driving it for about a week now, and haven't tested the voltage again. I'll be sure to do that.

However, here's the problem I'm wanting to get some help with. After charging the battery I drove the Jeep over to Autozone to have them test the alternator. When he tested it, he said that everything tested ok, but that the alternator was only putting out about 30 amps. After telling him it was only a 37 amp alternator, he seemed to think that would be fine. I drove home, but when I got home and pulled the Jeep in the garage I noticed my headlights were flashing on and off, as if I were turning them on and off, as opposed to dimming and coming back up. This wasn't just the headlights, but also the dash lights, and I'm assuming side markers and tail lights, but I haven't confirmed this. As it was daytime, I didn't notice it until I pulled in the garage.

I took the Jeep out again a few nights ago and didn't have any problems with the lights flashing while I was driving (moving), but when I would come to a stoplight and sit, they would start flashing, once I started driving again, they seemed to stay on, but once I would come to a stop they'd start flashing again.

I'm not sure what to make of all of this, especially since they're flashing on and off, as opposed to just dimming.

Any ideas what's going on?

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Unread 09-25-2011, 11:51 PM   #2
Cutlass327
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Is it more of a pulsing? Mine were doing that, where the lights would rhythmically be dim/bright/dim, but they never went out.. My volt meter would pulsate with them. Mine would do it at a frequency that increased with RPM, and then once it hit a certain RPM it would cut to half the frequency..

I took the alternator apart, planning to take the diodes out and test them, and then also swap from a spare alternator any parts needed, (Spare was the OE 36A, I have a 78A in it now) and I found that there was a bluing on the commutator rings of the rotor. I used some crocus cloth and polished the bluing off, and reassembled (diode trio was ok). Fired it up, and it is fine now. I've caught it doing it every now and then lately, so I figured I'll have to do it again some day. I'm guessing that leaving the key 'on' and not running has heated a spot on the rings where the brushes were sitting, causing the blue spots.
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1978 CJ5 258/T177/D300, '86 D30/D44 WT axles, 'glass tub windshield frame, and fenders, 31x10.5 BFG A/T, TDK galv'd frame - DD and weekend toy

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Unread 05-23-2014, 07:35 AM   #3
rahijada
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I know this is a really old thread, but wanted to update it to let everyone know what the problem was. Turns out the headlamp switch was the problem. It was old and I'm assuming had weak connections which would cause it to get really hot and that would cause it to fail. Once it cooled it would light up again until it overheated. Long story short a new switch has me up and running at night and my lights are so much brighter now too!
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Unread 05-23-2014, 07:44 AM   #4
Mike Romain
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Thanks for the update and a tip on the cause for you. The stock switches only are rated for stock headlight bulbs. If you put halogen headlights in, the breaker in the switch will eventually overheat and blow out again. The more high beam use, the faster it will get cooked. You need to wire in relays so the switch only triggers that and the headlights get direct fused battery power.

When halogens first came out they came with relays for this. Most modern vehicles come with relays.
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86/00 CJ7 Laredo, 33x9.5 BFG AT's, 'glass nose to tail in '00, 'New' frame,wires and plumbing in '09. Carter BBD Carbed 4.0 HO in '10.
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Unread 08-28-2014, 02:22 PM   #5
icecreamgetter
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Since this thread was brought back from the dead. I just recently picked up a 1978 CJ5 and am having the same issues. All lights - inside and out will flicker randomly when driving.

I turned on the hazards since I was moving and noticed that they still worked while the others flickered. So it appears the knob on the steering column was still able to initiate the blinkers. I assume that just like the OP noticed ...the switch in the dash is bad or something associated with that switch.

Questions: Is the switch hard to change out? It looks like I can pick up a switch at Autozone etc. Is it likely that it is the switch? ...or is there a relay or something similar involved that may be a more likely culprit?

I am new to the forum. I noticed that while searching the interwebs for info on Jeep stuff, this forum always came up with a ton of great valid info. So, here I am. Thanks for any help.

Last edited by icecreamgetter; 08-28-2014 at 02:57 PM..
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Unread 08-28-2014, 03:23 PM   #6
jeepdaddy2000
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FYI on pre 76 Jeeps, there is a circuit breaker mounted to the back of the headlight switch. Many times when you are fighting lights that flash off and on, the breaker is the issue, whether it is bad or the circuit is overloading.
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Unread 08-29-2014, 06:06 AM   #7
Mike Romain
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Quote:
Originally Posted by icecreamgetter View Post
Since this thread was brought back from the dead. I just recently picked up a 1978 CJ5 and am having the same issues. All lights - inside and out will flicker randomly when driving.

I turned on the hazards since I was moving and noticed that they still worked while the others flickered. So it appears the knob on the steering column was still able to initiate the blinkers. I assume that just like the OP noticed ...the switch in the dash is bad or something associated with that switch.

Questions: Is the switch hard to change out? It looks like I can pick up a switch at Autozone etc. Is it likely that it is the switch? ...or is there a relay or something similar involved that may be a more likely culprit?

I am new to the forum. I noticed that while searching the interwebs for info on Jeep stuff, this forum always came up with a ton of great valid info. So, here I am. Thanks for any help.
It is likely the breaker in the switch has worn out. Do your sealed beams say halogen on them? The emergency flashers are on their own fuse so they still work.

Switch is easy to change. Unhook battery first, then feel in the back of the switch for a button to push. When you push this and pull the headlights on, the shaft with the knob pulls right out the front, then you can unscrew the front bezel and remove the switch.
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86/00 CJ7 Laredo, 33x9.5 BFG AT's, 'glass nose to tail in '00, 'New' frame,wires and plumbing in '09. Carter BBD Carbed 4.0 HO in '10.
89 YJ Renegade. BBD Carbed 4.0 HO. Locked front and rear with 33x9.5 BFG AT's
Some Canadian Bush Jeep Runs and Build Photos: http://mikeromainjeeptrips.shutterfly.com (10 new albums added Sept 16/10)
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Unread 08-29-2014, 06:20 AM   #8
Matt1981CJ7
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The main problem with CJ lights is how they are wired. The power runs from the battery thru the dash to the switch, then from the switch all the way out to the lights. The factory used small gauge wires with highly resistive contacts for these lengthy circuits, which causes an excessive voltage drop at the headlights.

The solution is to shorten the power path by using relays, which are simply an electrical switch. When the relays get power from the headlight switch, they complete a circuit from the battery directly to the headlights. Since this new circuit uses heavier wire, fewer contacts, and is a shorter distance from the battery to the headlights, the voltage drop is virtually eliminated.

Here's my lighting upgrade thread that may help some of you.

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Unread 08-29-2014, 07:56 AM   #9
zillla
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Never mind.... I am responding to ancient history
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Unread 08-29-2014, 09:06 AM   #10
Mike Romain
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Originally Posted by zillla View Post
Never mind.... I am responding to ancient history
No, you are Ok still, the old thread was hijacked a second time yesterday by a new poster with similar problems. He should have started his own thread to avoid confusion, but here we are...
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86/00 CJ7 Laredo, 33x9.5 BFG AT's, 'glass nose to tail in '00, 'New' frame,wires and plumbing in '09. Carter BBD Carbed 4.0 HO in '10.
89 YJ Renegade. BBD Carbed 4.0 HO. Locked front and rear with 33x9.5 BFG AT's
Some Canadian Bush Jeep Runs and Build Photos: http://mikeromainjeeptrips.shutterfly.com (10 new albums added Sept 16/10)
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Unread 08-30-2014, 01:54 AM   #11
icecreamgetter
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Sorry for not starting a new thread. But had I gone that route, someone else would have told me to "use the search function". Since I was dealing with the same issue, I figured using the same thread would consolidate information from multiple people with similar issues.

As it turns out, I did purchase a new switch and swap it out. Easy fix and it did solve the issue. The flickering first happened when my wife was driving the other night and it freaked her out. She was afraid to drive the CJ until I could prove I had fixed the issue. Thanks to both the OP who PM'd me and those who gave answers in this thread.
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Unread 08-30-2014, 04:17 AM   #12
doctorchopper
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Quote:
Originally Posted by icecreamgetter View Post
Sorry for not starting a new thread. But had I gone that route, someone else would have told me to "use the search function". Since I was dealing with the same issue, I figured using the same thread would consolidate information from multiple people with similar issues.

As it turns out, I did purchase a new switch and swap it out. Easy fix and it did solve the issue. The flickering first happened when my wife was driving the other night and it freaked her out. She was afraid to drive the CJ until I could prove I had fixed the issue. Thanks to both the OP who PM'd me and those who gave answers in this thread.
Good to hear that its sorted, but I'd still recommend doing the relay mod as the switch will probably burn out again, it's a fairly quick and easy as well as cheap mod to do
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Unread 08-30-2014, 09:10 AM   #13
icecreamgetter
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Originally Posted by doctorchopper View Post
Good to hear that its sorted, but I'd still recommend doing the relay mod as the switch will probably burn out again, it's a fairly quick and easy as well as cheap mod to do
Thanks for the input. I would like to do the relay mod as well.
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