Electrical problem, Brake lights Turns

[EZGZ]

Howdy Folks,

Subscribed to TDR back in 96 and have full library of all the registers. Got a computer a while back but never thought of coming here to check in.



Anyway, Got a prob with my 91. 5 LE. She starts and runs fine and the battery stays up but I have a issue with my Brake-lights and turns, Cruise. Using any of these items blows the fuse and the anti-lock light comes on. Started out just ounce and the fuse took care of it but now it is really jacked up. If you hold the fuse block in your hand and lift it you can hear a buzz, lower it down it goes away. I replaced the fuse and let it hang to get home. The brake lights would work but activate anything else and it takes out the fuse.

Can't see any loose wires and have a pretty good electrical background and a good fluke meter. Just not seeing anything obvious. Checked the bulbs and trailer connectors. Doesn't't matter if I have the trailer hooked up or not.



I have tried to hunt in the TDR archives and tech tips and read something about bad fuse blocks and them not being available?? (yikes)



I don't want to just tear into this if it has a history of problems on this truck. I have had her since 96 and she has served me well. Thought maybe someone out there might have had a similar nightmare and know a easy fix

I have a friend with a 89 and he says his has always given him trouble and the problem comes and goes.

If someone could point me in the right direction or knows a fix I would be thankful.



Seems like a nice bunch of knowledgeable folks here. I might just hang out and offer what I can. I have been around the block a few times, done some mods and even been through the Getrag ounce. I soon decided with the 4:10 gears I wasn't going to get there any sooner and finally backed off the pump and just enjoy the hill climbs. I save the speed thrills for my little 99 F150 Lightning and VW sandrail.



Oh Well, enough about me, anyone got a suggestion on my electrical prob.

Thanks in advance

 

[Philip]

The items you are having problems with go threw the main switch. Check your harness going up to the clock work switch and see if the wire are chafed in any places. This has been a problem with the 1st gens.



While you have the column covers off. Check and see if the switch itself is getting hot. A couple of people have had switches go bad.

 

[EZGZ]

Thanks for the quick reply.

Just a tad bit more info please.



That clockwork switch you speak of must be the ignition Key switch. Right?

Start digging in the steering colum correct?

 

[Philip]

The one you need to check is called the multi function switch. The ing switch is the other one located on the steering column. All the items you are having problems with go threw the multi function switch. Turn/brake/cruise.



So look the wiring over going up the column very close for bad spots. If there are no chaffing on the harness the its going to get harder to trouble shoot. You will need to find the wire for each circuit to test amperage draw.



The buzzing when you place the fuse block in a certain position. I don't like the sound of that.



Do you have a factory manual?

 

[EZGZ]

Factory Manual?

Did I mention my middle name is procrastinate?

I had a buddy who owned one for an 89 but he got rid of it with the truck.

I will take a look at it after breakfast.



On DC current using an DC Amp meter I will have to rig up some test leads to use it in series Right? That means I would have to cut each wire to Amp it unless I can find a connector.



I am thinking my clamp on fluke meter with ac amp attachment won't be much help. Right?



I guess I could just get a 12 volt Dash style amp meter from checkers or something. I am thinking that won't be accurate enough for comparison's. I am spoiled from all the digital technology.



I need some coffee, and a couple asprin

 

[Philip]

Most flukes will not do DC amps with the clamp on. But you can do it threw the miliamp section. But you are limited to 10 amps max. Or at least mine is rated at 10 amp.



I also have a clamp on stand alone MAC DC amp meter I use.

 

[EZGZ]

Thanks Phillip!

I am slow about getting up the nerve to go out in the snow and try this. I may work on running a gas line to my new garage heater and make this one of my first projects. I will keep you posted if I find anything of interest.

Later

Greg Z

 

[HonkinDiesel]

Good Morning EZGZ

Having a wee bit of electrical trouble are we. I just got up sitting down with my coffee, Lets see if we can help a little. I hope you have a little electrical knowledge at least. Otherwise this may get real complicated and I would have to refer you to the dreaded garage shop where $$$ will leave your pockets(usually).



Since no one else has posted this kind of procedure, I'll try and run you through basic steps of electrical trouble shooting. If you are not comfortable with is procedure, don't do it!



I don't suggest using the current function on your multimeter, at least not yet. If a circuit is taking out fuses then it will probably take out the one in your meter!



If you have a DC type current clamp, this is better. Otherwise AC current clamps do not work on DC circuits.



Disconnect your battery as we proceed. I don't want to here that you got injured in this process! Your battery holds a lot of energy that can cause it to explode or ignite a fire.



As Philip suggested you are going to need to checkout all of your surrounding wiring harness.



Check the harness where it passes through the fire wall too. Make sure it has not chaffed through check it carefully because all it takes is a nick through the insulation to chassis. In case of doubt insulate the location with electrical tape and use new gromets or bushings. If you find a cut wire or severly damaged one you will need to butt splice it with crimp type connectors. Do not just strip, twist wires together and wrap with tape. NOT good!

Apply this method through out.



Buzzing comming from the terminal block is rather bizzare as the only thing I think you have on it is the turn signal or flasher relay. Anyway check the back of the fuse panel to make sure all connections are secure and where they are supposed to be.



Still have not found the problem!. Here is where you roll up sleeves and let out a deep sigh! and here is where it gets complicated!



To help possibly narrowing the problem down further and since you have fuse(s) blowing. Believe it or not this is a good thing! Check the circuit for which it controls. A manual with schematic would be good right about now. I have the manual, unfortunately no scanner, but I could take a digital picture of the page(s) and email it to you if needed.



OK Lets walk through this thing!



Take out the fuse which is blown and switch off all circuits that is on that circuit and use your multimeter on the ohms function (if it has a audible continuity checker use it here).



With one lead on the grounded/common/bare metal part of your truck chassis, check the continuity of the circuit by using the other lead to probe the fuse socket on the LOAD side of the fuse socket.



Note: The battery side of the fuse can be identified on the back of the fuse block where the main (battery positive) lead is distributed to the other fuse terminals, The opposite side of the fuse is the LOAD side.



Make sure you move the block around because the fault maybe intermittant.

If your meter detects continuity then you are one step closer to finding out the problem. (Go to next paragraph) Boy flow charting this stuff would be handy!

If no continuity check the other side of the fuse terminal just in case you picked the wrong side to begin with.

If no continuity try activating (switching) on circuits for which that line is supposed to control.

Still no continuity, re-check the above steps again and then send me an E-mail (PM), I'll try to work it through with you further.



If you found continuity (great!) you are now on your way to finding the fault. Continue tracing the wire fro the fuse block to that circuit for which it controls and check it carefully for defects (and repair it as previously discussed)



Once you have thought that you found and repaired the problem replace the fuse (with a good one of coarse and of the same current rating), reconnect the battery and startup the truck and check if electrical operation is how it should be. If not, you have not found the problem yet and you need to go back re-check the circuit (If you are still stuck, PM me with what you have found and done).



Good luck bud! Happy hunting! You may soon know why they charge the big $$$ for electrical problems

 

[prototech]

Hey Greg,

I recommend checking your trailer wiring connections on the truck, I have seen many problems in that area and chances are its not a factory tow package and if you didn't install it yourself that might be a good place to start. all of the systems you explained run to your trailer wiring. Also I recently had a problem with my electronic brake control, it shorted out and blew the same fuse I think you're having trouble with. hope this helps!

Proto

p. s. I hate the cold too! have so many things I want to fix or improve on my truck, but the cold sure kills my ambition!Oo.

 

[EZGZ]

Ok fella's

After a trip to the store to get a dedicated torx driver instead of my shorty assortment. I got the column shrouds off and every thing looked great. All the wires were neatly tucked in the plastic covers and in the proper place.

No signs of chafing or anything.



The buss bars on the bottom of the fuse holder were not discoloered in any way.

No buzzing this time.

"The fuse was not blown" but no brake lights or turns.

Replaced the turn signal flasher. (The old one had a old peace of masking tape over it from days of yore but not by me and not suspicious. The only time I am reading voltage is when I turn off the key which of course opens the circuit and allows it to go through my volt meter.



Could not get an amp reading but am seeing 13 Volts.

Looked up by the firewall and that also looks good.



I suppose the next step is to crawl under it and start checking all the camper and trailer connections.



Running lights, heater, etc are all working fine. Pulled the drivers side tail light off and checked the bulb again. OK. Was easier to leave it hang in the wind and try the brakes etc.



Will continue the search another day. The wind kicked up and I am cold to the bone.



Without a book and schematic I am at a loss. Don't know where the ground is for this circuit.



In Conclusion:

The problem has now gone from the fuse blowing to nothing happening and the fuse and voltage at the fuse block is correct.

Must have finally broken the power wire after the fuse leaving the circut open and the fuse good untill such time as that contacts ground.



Am I on the right track here or headed to La La land.

Thanks

 

[Philip]

Check your battery ground wire to body. That is the small wire coming off the neg terminal. It has been know to loose ground before. It was not connected to bare metal during assy. There is paint under the terminal on the raditor support.

 

[EZGZ]

TTT to the top



Hey guys,

Thought I would post an update on this since it is long overdue.



My mystery problem was finaly solved after wasting a lot of time in the cab crying a sobbing and fumbling with my fluke meter.



Found the problem was in one of my little used trailer connectors in the back bumper. I usually use my large 7 connector but I allso had a smaller 6 pin that got little use. Evidently moisture got in there or at some point one of the pins broke and fell down laying on some others. It must have gotten real hot cause it did considerable damage before effecting a fuse. Must have been intermittent and went on for some time.

Anyhow, I removed that plug and now just use the big 7 blade connector and I am amazed at how bright my lights have become and my turn signal flasher work better to.

Thank you all for your support and suggestions.

Me a happy camper again.

Greg Oo.