turn signal gremlins

[alkmisc]

So I've got some electrical gremlins in my turn signals with "hyperflashing" on the bad (passenger) side. So after changing out bulbs and cleaning sockets, here is what I have:

On the presumed good side with headlights on and no turn signal: inner amber light is lit, outer is not (I thought that was supposed to be lit but could be wrong).

Good side headlights on, turn signal on: amber lights and side marker flash alternately.

Good side headlights off, turn signal on: amber lights and side marker flash together.

Bad side headlights on, turn signal off: no amber lights or side marker.

Bad side headlights on, turn signal on: amber lights and side marker flash together and are dim, hyper flash and now some slower flashing.

Bad side headlights off, turn signal on: amber lights and side marker flash together and are dim, hyper flash.

Headlights off, hazards on: all lights flash together, no hyperflash but dim on the bad side.

Headlights on, hazards on: amber and side marker on good side flash alternately, amber and side marker on bad side flash together and are dim but no hyper flashing.

Note that all tail lights are the same brightness and flash at the same rate as the corresponding front lights. Headlights are on a relay harness but that shouldn't be affecting the turn signals which are still on the factory wiring.

I'll be checking and cleaning grounds when there is more daylight out but I'm looking for other ideas or suggestions of things to check, maybe a relay somewhere? And where are the most relevant grounds (I think there are a couple on the radiator support and there's that one on the passenger side body by the battery)?

 

[3500GMC]

Grounds first. Play with your turn signal switch as well, it can cause strange signal problems.

 

[alkmisc]

So there was a big ground problem - passenger side ground was loose. Tightening the passenger side body ground worked for now but who knows how long before it loosens again since it's just screwed into sheet metal. I think the threads of the screw are not biting like they used to or the hole is getting out of shape. Any ideas for making that ground stay put better in the future?

The stray turn signal lamp that went out on the good side stayed out with headlights on but blinked when the turn signal was on. I cleaned the socket again and noticed there was a fair amount of yellow grease in the socket that didn't come out the first cleaning but that seemed to fix that so it works like it should. Still not sure why the bulb was only completing the circuit when flashing though.

 

[schiker]

You can add a ground. The frame and body is like a big buss bar you can add to it and its pretty forgiving. Probably should be careful around electronics and wet locations like radiator and engine and or something with a whole lot of current but adding and tuning up body and light grounds is pretty safe.

I added extra grounds to my batteries. Passenger extra ground to rear of engine ground and drivers side extra ground to body fender.

 

[alkmisc]

Is the insulation by that passenger side body ground necessary? I'm tempted to cut away a piece of it and put in a rivnut so I can bolt the grounds on rather than rely on a sheet metal screw. Also, what risk is there in running some of the grounds directly to the battery ground terminal? I have a couple of headlight harness grounds that are screwed to the same place as the body ground which essentially is a straight path to the battery.

 

[schiker]

A ground strap or connecting strap doesn't really need insulation. I guess the negative battery cable doesn't really need insulation except in the vicinity of a wrench or other conductor touching it from the positive side. And you want it covered to reduce any corrosion build up. And minimize any corrosion of the conductor inside the insulation.

But the "tail" of circuit I like to keep insulated. If the tail of a circuit comes off ground it can have some voltage relative to ground but current will be limited to resistance of circuit. For a bulb no biggie but its good practice to understand the end wire of a circuit or "tail" wire to ground is only neutral or ground when it is actually touching ground otherwise it is might be hot.

For a major load or some auxiliary circuit I might run a wire back to the battery but a clean connection to frame or sheet metal should be good if battery grounds and body and or connectivity grounds are good. I consider the strap from frame to motor a connectivity ground. You can't run all the circuits back to battery ground it would be a mess so its best to keep the major grounds in good shape at both ends. Especially the battery and frame/body/motor ends.

 

[WarWagon]

The "straight path to the battery" isn't. The main ground strap to the engine is a bigger low resistance connection than the small wire we get.

Grounds run to the battery terminal "sink" the voltage of the battery and cause undercharging. Battery charge is critical by 0.1volts. 12.6 needs a charge and 12.8 is fully charged for example. Add temperature compensated charging and a specific voltage goes out the window. In a dual battery system any uneven voltages can under or over charge one of the two and the undercharged drains the higher charged battery and they both sulfate to death.

So a ground tied to the battery has to run down the battery cable to the "bad connection" at the engine. Then it has to go to the alternator. The "extra" current on the battery ground cable will cause a voltage. This voltage reduces the charging voltage at the battery. Makes dual battery system uneven because the current is never even to grounds run to the two batteries.

Next major "you let the magic smoke out" event of grounds run directly to the battery...
Battery big ground cable gets a loose bolt or corrosion build up. If the charging current doesn't smoke off your ground wire and burn up differential bearings and other things in the "new" ground path:
Hitting the starter will turn the small ground wire into a fusible link.

Corrosion is the worst at the battery terminal and can eat the entire ground wire off. At the minimum you have to service the grounds way more often.

GM on Trailblazers uses the battery connection to bridge the engine and body. It is a horrible bean counter cheap design with 0.5v between the engine and body readings.

 

[Will L.]

If you can read voltage anywhere on a grounding circuit you have too much resistance too ground, in other words a bad ground.

The only reason there is insulation on any ground wire anywhere is to keep the wire from corrosion. If you want to replace a sheet metal screw with a bolt and nut, do it. Remove the paint from the metal where your new eyelet goes on and your good. The sheet metal screws were used because they are cheaper, bolt and nut is better.

The more points of connection directly at the battery is the concern of messing with charging system. Also the more points of contact with more dissimilar metals increase problems at the battery post. Gm, like most mfrs, use "just big enough" wiring to get the job done but copper costs is a high percentage so they save every penny they can. That's why everyone that buys Bruce's bigger battery cables then comments on how much better the truck starts. If they tracked battery life, they would figure out longer life there also.

When it comes to grounds, run the largest size in the shortest length you possibly can. You should not need to run any factory lighting circuits back directly to the battery, mounting in the factory area with new connectors and clean metal should be good. But if you attach one temporarily and can see an improvement, that tells you that body panel is not properly grounded. Rusty bolts that hold panels create problems like this, so put a meter in between the grounding location and the battery post to ensure it is a good ground.

 

[jrsavoie]

On a related note. The lights all seem to work fine on the 1995 Tahoe. But when you put the left turn signal on, it flashes fast like I have a light out.

 

[alkmisc]

Thanks for the background info. I'm thinking I'll go with putting in a rivnut and bolt on that passenger side. It'll be much more secure than the sheetmetal screw we get. The insulation I was referring to was the large pad by the sidewall. All the insulation stays on my cables. I do have Bruce's battery cables - a custom set for top post batteries - very nice improvement over factory!

 

[jrsavoie]

Thanks for the background info. I'm thinking I'll go with putting in a rivnut and bolt on that passenger side. It'll be much more secure than the sheetmetal screw we get. The insulation I was referring to was the large pad by the sidewall. All the insulation stays on my cables. I do have Bruce's battery cables - a custom set for top post batteries - very nice improvement over factory!

I always add a ground to the battery box bolt to compensate for that bad ground. I had problems with it stripping and just never liked them.

 

[Will L.]

Rivnut? I missed that earlier. The connector has to come in contact with the metal that is grounded. I don't know if I would use that because the ground is being carried through the rivnut body to the sheetmetal. A bolt will only apply clamping force holding the connector against the grounding suface. If the "squished" protion of the rivnut gets corrosion behind it or comes loose you will be back at square one.

 

[jrsavoie]

I pull the battery out, use a 5/16 eyelet, a star washer, 3/8" eyelet and about 12" of 10 ga. stranded wire. I take a bolt out the battery box to fender, coat everything with kopr kote solder the eyelets and connect the 5/16 to the battery box and the 3/8 eyelet to the battery

 

[alkmisc]

I'm hoping that area will stay fairly protected from the elements (right now it seems to be) so that any corrosion will take a long time to develop. I do like some of the other ideas about the battery box - seems more permanent.

Rivnut? I missed that earlier. The connector has to come in contact with the metal that is grounded. I don't know if I would use that because the ground is being carried through the rivnut body to the sheetmetal. A bolt will only apply clamping force holding the connector against the grounding suface. If the "squished" protion of the rivnut gets corrosion behind it or comes loose you will be back at square one.

 

[jrsavoie]

And the bolt is already there. Just take it out, clean it up and reinstall. I always put a stainless or brass washer on top of eyelets so they do not want to turn when you tighten the bolt. Sometimes a star washer under the eyelet

 

[Will L.]

I pull the battery out, use a 5/16 eyelet, a star washer, 3/8" eyelet and about 12" of 10 ga. stranded wire. I take a bolt out the battery box to fender, coat everything with kopr kote solder the eyelets and connect the 5/16 to the battery box and the 3/8 eyelet to the battery

Yup! Good answer! Do that exactly.