Scared Sh#%&less

[cgallamore]

driveing along just west of denver,co. on I 70 about 8 pm just starting up the mountain had a good run at it and my headlights went out. could not see the dog. never have i had an adreniline rush like that, tried light switch, dimmer switch, grabbed 4way flashers got enough light from them to see the painted stripes, got onto the sholder turned off light switch for about 30 seconds, turned it back on and they worked fine. i changed my pants, made it to the first exit, opened hood, shook wires and plugs for over an hour, never got anything to blink. waited till day light proceeded on to western colarodo mack very nice staff worked on it for over 3hrs, took apart dash checked everything. they could not find any problems it has the updated harness. nothin looked liked it had been hot or rubbing. the bigest problem now is trust untill i get home and install seperate running lights for backup. has anybody else had this problem?

during the time the lights were off the dash lights,marker lihts, were still working fine

[HK Trucking]

The Problem is in the headlight circuit which is separate from the circuits that power the taillights marker lights & dash lights.

I've been reading about your ongoing problems with that truck for some time now, does your state have a "lemon law"?

It sure seems that truck is broke down more than it's working. That makes it pretty tough to make a living, and headlight failure out on the highway like that could result in disaster.

[Rob]

And it's not a Pete, (which would be perfectly natural). What Herb states is correct on the headlamp and other circuits being separated. However, the left and right circuits are usually separate from each other also and protected by self resetting individual breakers, (not fuses). In order to lose illumination to the headlamp circuit there would need to be a common control point which would either be the headlamp switch, headlamp dimmer switch, or the interconnecting wiring. With them comming back on a time later could be the circuit breakers had time to cool and reset, or the changing of the headlamp switch position could have "jossled" their contacts position. The internal construction of automotive headlamp switches consist of copper strips, and fingers used for contacts and are are thin, typically serving the life of the vehicle, but not always.......

Intermittent problems like this are very difficult to isolate and repair. Coupled with the unpredictable frequency of recurrance they can be great generator of undue stress......

If the weather was clear and bright at the time of the problem, change the headlamp switch as cheap insurance. Some of these things run warm and can break down internally in addition to not being of the best quality construction. If the weather was moist or humid, look for wiring issues along the floor pan, and firewall of the cab for moisture intrusion and corrosion; especially at the connection plugs. A wee bit of corrosion, or moisture in these can wreak havoc on electrical systems. I don't really see taking the dash apart again unless there is room for doubt in the technicians' ability that evaluated the problem.

Rob

[fjh]

And it's not a Pete, (which would be perfectly natural). What Herb states is correct on the headlamp and other circuits being separated. However, the left and right circuits are usually separate from each other also and protected by self resetting individual breakers, (not fuses). In order to lose illumination to the headlamp circuit there would need to be a common control point which would either be the headlamp switch, headlamp dimmer switch, or the interconnecting wiring. With them comming back on a time later could be the circuit breakers had time to cool and reset, or the changing of the headlamp switch position could have "jossled" their contacts position. The internal construction of automotive headlamp switches consist of copper strips, and fingers used for contacts and are are thin, typically serving the life of the vehicle, but not always.......

Intermittent problems like this are very difficult to isolate and repair. Coupled with the unpredictable frequency of recurrance they can be great generator of undue stress......

If the weather was clear and bright at the time of the problem, change the headlamp switch as cheap insurance. Some of these things run warm and can break down internally in addition to not being of the best quality construction. If the weather was moist or humid, look for wiring issues along the floor pan, and firewall of the cab for moisture intrusion and corrosion; especially at the connection plugs. A wee bit of corrosion, or moisture in these can wreak havoc on electrical systems. I don't really see taking the dash apart again unless there is room for doubt in the technicians' ability that evaluated the problem.

Rob

I agree with Rob here replace that HL switch somthing told those relays to shut down All at once ,that relay arangement,(The Update} was ment to take the load off the HL switch, Maybe it got installed a little to late to save the switch!

[log hauler]

Had the same thing happen to me twice in my 2002 Vision, used the fog lights to get off the interstate. Both times it was the headlight switch in the dash. I carry a spare with me now

[RowdyRebel]

I had that happen in my '01 CH...pulled in for fuel at 2:00 AM and cut the headlights. When I went to leave the truck stop, headlights would not come back on. I pulled the switch and rigged up a switch that would get me by....it worked until I got the new switch the next day. Put the new switch in and THOUGHT I had the problem fixed....and a month or so later it happened again. I'd pull the cubby hole out of the dash and the lights would come on. Sometimes I'd have to reach in through the cubby hole opening and jiggle some wires and they'd come on...DEFINITELY a wiring problem, but I haven't been able to locate it yet. Every time I pull the dash panel out, I go over all of the wires and trace the connections as far as I can...still haven't found anything but (knock on wood) been working for the past several months problem free.

One thing you may want to try if it happens again, I know the switch on the turn signal lever that flashes the high beams WOULD turn on the high beams...so if you are running down the road and it happens again, try hitting that switch. High beams may bug the heck out of everyone around you, but they'll let you see where you are going until you can find a safe place to get off the road and jiggle some wires.

[Double L]

Just beware with the high beam trick of flying pee bottles and one finger salutes.

[theakerstwo]

Sounds like you need some driving lights.I am to scared of the dark.This keeps up the Lord is going to reach over and tap you on the arm and say come on son its time to go home.

[Mack 3P]

Your truck may need to go to the dealer. Check your VIN with your dealer. I attached an older copy of the bulletin.

SC342_edit.pdf

[cgallamore]

I had that happen in my '01 CH...pulled in for fuel at 2:00 AM and cut the headlights. When I went to leave the truck stop, headlights would not come back on. I pulled the switch and rigged up a switch that would get me by....it worked until I got the new switch the next day. Put the new switch in and THOUGHT I had the problem fixed....and a month or so later it happened again. I'd pull the cubby hole out of the dash and the lights would come on. Sometimes I'd have to reach in through the cubby hole opening and jiggle some wires and they'd come on...DEFINITELY a wiring problem, but I haven't been able to locate it yet. Every time I pull the dash panel out, I go over all of the wires and trace the connections as far as I can...still haven't found anything but (knock on wood) been working for the past several months problem free.

One thing you may want to try if it happens again, I know the switch on the turn signal lever that flashes the high beams WOULD turn on the high beams...so if you are running down the road and it happens again, try hitting that switch. High beams may bug the heck out of everyone around you, but they'll let you see where you are going until you can find a safe place to get off the road and jiggle some wires.

[cgallamore]

tried the high beem button, got nothing. spent the first 3-5 seconds flip switch high beem, low beem, high beem flash for pass, and turning on 4ways. next 5 seconds waiting for my eyes to adjust enough to see the painted lines,and figured out turn off head light switch to kill dash lights helped the hole time wishing i had fog lights.

the next day i thought maybe it was a circiut breaker,i removed panel and noticed on the diagrahm the cig liter was a 20 amp next to head light wich is 25 amp thought i would switch them wat the heck,they had allready been switched.

the rocky mountains is a missarable place to be when you have lost faith in your equipment!

[Speed]

I'm with Theakerstwo;

I'd get a pair of road lights,and wire 'em from the key switch,so you don't forget to shut 'em off and kill the battery. Also,add a separate fuse as close to the power source as possible. And be sure to adjust 'em at night,without the headlights on,for the best vision without blinding the whole county. Even after you get the headlight problem sorted out,they're still good for a back up,in case a flock of night hawks takes out your headlights. Don't ask how I came up with this particular example....

Speed

[Gambi80]

I would definately rig up some sort of driving lights via a seperate switch/power source. The more light the better in my opinion.

I have a problem with the instrument panel lights. The lights for the switches and whatnot work, but not the gauges sometimes. If I take the panel out and jiggle the wires they'll light up. Sometimes they'll work as they should. Kind of a crap shoot at times with my 'old' truck. But seeing that one guy advertising his 97 for $29,500 gives me hope!

[mackcl96]

Your truck may have been already wired for fog lights,(99% of the C models had this harness) Check between the bumper and the radiator for two plugs with dust caps.If you have them then in the dash you will have a plug laying in there and probably need to add a fuse

[cgallamore]

i would like to take this time to thank the dumasses at flag truck center who kept saying they knew what they were doing.after only three hrs. of trying to find the problem they told me maybe i should just drive during the daylight because the problem was undiagnosable, untill they went out and stayed out. i guess i should have went to autozone and bought them a amp meter. i pulled into st.louis mack first thing they did was check amp draw,18.6 amps it should draw between 18 /20 amps but with only a 20 amp fuse it would pop sooner rather than later. it had the wrong fuss in the head lights,it took f@c mack in st.louis every bit of 5 min. to find it.

[Rob]

i would like to take this time to thank the dumasses at flag truck center who kept saying they knew what they were doing.after only three hrs. of trying to find the problem they told me maybe i should just drive during the daylight because the problem was undiagnosable, untill they went out and stayed out. i guess i should have went to autozone and bought them a amp meter. i pulled into st.louis mack first thing they did was check amp draw,18.6 amps it should draw between 18 /20 amps but with only a 20 amp fuse it would pop sooner rather than later. it had the wrong fuss in the head lights,it took f@c mack in st.louis every bit of 5 min. to find it.

I'm afraid you have lost me here. If you have an 18.6 ampere draw on a 20 ampere rated fuse and it blows, there could be another problem. Although I typically size an electrical load with a 20% "safety factor" built in at no time should the current draw mentioned force the circuit interrupter to act, (blow). Automotive fuses are built to be "slo blow" to withstand the instantaneous inrush current which is always much higher than once the circuit stabilizes such as the lamps illuminating.

I remember your problems with lamps extinguishing during operation and hopefully the headlamp switch has been replaced as this has been problematic to others. I would be inspecting your wiring harnesses for water intrusion/corrosion and while using an ammeter tied into a main headlamp circuit feed, manipulate these harnesses and look for surges on the meter. I feel it is this sudden increase in current that causes your problem if the headlamp switch has been replaced, the the problems still exist.

Rob

[cgallamore]

i have installed driving lights rerouted its power source to be independant of the headlights and will do this on every truck i drive from now on.

i had let the truck run for several hours with lights on befor going to dealership as i did at other shop. tech. at f@c came and got me rite away to show me how hot circuit breaker was and explained the age of the breaker and running at full load could cause it to trip. and to leave pannel cover off and feel new breaker often for a while. and to try the 20 amp breaker during daylight to see if their is noticeable difference,the 25 amp gets warm but the 20 amp gets to hot to hold. as at the other shops they checked all conectors,rellays,wiring harness,switch,and i carry an extra switch with me now. and we checked another vision to see wwhat it was pulling 19.6 amps.i am not a mechanic but they took the time to walk me threw what they were doing while they were doing it made me a lot more confident in the diagnosis.

[Rob]

i have installed driving lights rerouted its power source to be independant of the headlights and will do this on every truck i drive from now on.

i had let the truck run for several hours with lights on befor going to dealership as i did at other shop. tech. at f@c came and got me rite away to show me how hot circuit breaker was and explained the age of the breaker and running at full load could cause it to trip. and to leave pannel cover off and feel new breaker often for a while. and to try the 20 amp breaker during daylight to see if their is noticeable difference,the 25 amp gets warm but the 20 amp gets to hot to hold. as at the other shops they checked all conectors,rellays,wiring harness,switch,and i carry an extra switch with me now. and we checked another vision to see wwhat it was pulling 19.6 amps.i am not a mechanic but they took the time to walk me threw what they were doing while they were doing it made me a lot more confident in the diagnosis.

It does sound as if they did a good job for you. It also sounds like the circuit is not heavy enough, or marginal in the function it is to perform. You have done well in rerouting the current required for the driving lamps away from the existing wiring. Hopefully you do not rely on a switch alone for the current to power the new lights but rather a definate purpose contactor specifically engineered for the job. These are routinely referred to as a "relay", but are in reality a "contactor". Relays are actually for switching small signals but the term is misused as they are not for switching large loads.

Don't mean to be so proper in the general sense, but I make a living working with this stuff and cannot be ambigious in my explanations.

Rob

[cgallamore]

used existing wiring for driving lights just moved power source from headlight switch to fuse panell. i check driving light function when i do daily inspection, but do not use them, they are for emergency only. i want to make sure they are not used up when i need them

[Rob]

used existing wiring for driving lights just moved power source from headlight switch to fuse panell. i check driving light function when i do daily inspection, but do not use them, they are for emergency only. i want to make sure they are not used up when i need them

I am assuming that your driving lamps were an OEM supplied part installed by Mack? If this is the case you will probably be alright. I do not like to use existing wiring if installing aftermarket lamps. OEM driving lamps rarely exceed 55 watts, (H3 type bulbs) and therefore are acceptable in the original wiring. Aftermarket replacements can exceed 100 watts and need larger wiring and aforementioned heavy contactors to safely carry the electrical loading.

Rob

[cgallamore]

yes they are oem i took off the lights that were installed by flagstaff mack they were after market pos and they cut the plugs off my truck. i bought oem plugs put back on my truck and had a set of oem lights off my 01 cl, had f@c redo wiring flagstaff had some mickymouse bs looked like 10 year old did it.

appreciate the attention to detail keeps me from overlooking somthing

[Rob]

Sounds like you try to do things right. I hate comebacks due to faulty or cheap workmanship especially when it had to be paid for.

I think you'll be set as far as this problem.

Good luck.

Rob

[cgallamore]

i havent got the bill from f@c yet it looks like that wrong circiut breaker has cost me at least 700.00$ so far. i gave it to my olady for christmas and told her its been awhile since you got a gift that cost that much from me.

[convoyduel]

Glad to hear Rick and the bunch at F&C took care of it. In my experience, their service and parts departments are A+.

Did you buy the Vision there? I think I saw your old CL on their lot not long ago.

[cgallamore]

got the vision that had been frount row for three years. traded a single axle ih and a skidsteer for it. they already sold the skidsteer but the ih is still there.