instrument panel warning lights

[blownalcohol]

Well its warming up so I am working out bugs in truck 2. Its a 720 2dr 4x4. A little bit of a Frankenstein as I have utilized a lot of ST stuff from the local u pull and pay. I upgraded to a cluster with clock, tach, gauges and I upgraded to a center console with voltmeter and oil pressure gauge. It also got a tilt column and upgraded to intermittent wipers. I have a factory manual and wiring diagrams, I did have to install a different oil pressure switch and add a wire to a section of under hood harness for the console gauges but everything else was pretty much plug and play. Everything seems to work fine except except for one annoyance.

 

If I have the lights on, and turn signal on the alt light pulsates dimly in relationship to the flasher. You can only see it at night. If the truck is stationary and the emergency brake is on the brake warning light in the cluster is on but if you turn on the turn signal the warning lamp will pulsate in and out, bright dim, again in relationship to the flasher. The voltmeter in the console also reflects a significant voltage drop that correlates with the flasher. I replaced the alternator without even checking it because I figured I had a bad diode in the rectifier. But that fixed nothing. I wanted to put a 60 amp in it anyway so that's done. I have checked the charging system at the battery with a Sun VAT 40. Its charging at as much as 60 amps and voltage is steady at 14-14.5. The VAT-40 doesn't show the same voltage fluctuation at the battery that I see from the gauge in the console.  I have checked every ground I could find, I've had more than one cluster of the same type in it, The 4 way flashers do not have they same dramatic effect as the turn signal does. That seemed odd to me so I've tried different flashers too, it changed nothing. 

 

The battery never goes dead and it starts every time. All of the exterior lights work fine, no hiccups. I have a lot of work in this truck and would really love to solve this little annoyance. Anyone been there? Need a fix. 

 

 

[datzenmike]

 When the the flasher turns the front and rear turn lamps on it's a huge current draw initially, and the voltage will drop slightly until the lamps reach full brightness. The #4 fuse powers the turn signals and what a surprise! the charge warning lamps is on it also and also the brake warning lamp.. So any sudden draw is going to cause the charge lamp to come on faintly.

 

Try replacing the #4 fuse? Maybe poor contact?

 

Only way to prevent this would be to lower the current draw by replacing the signal bulbs with LEDs.

[bottomwatcher]

If you go the led route I think the original flasher module has issues, not enough draw. I had to put resisters in another vehicle with a simular flasher.

[datzenmike]

Get the electronic flasher that is not load dependent. Next time in a junk yard pull one from an old car or ruck.

[blownalcohol]

 When the the flasher turns the front and rear turn lamps on it's a huge current draw initially, and the voltage will drop slightly until the lamps reach full brightness. The #4 fuse powers the turn signals and what a surprise! the charge warning lamps is on it also and also the brake warning lamp.. So any sudden draw is going to cause the charge lamp to come on faintly.

 

Try replacing the #4 fuse? Maybe poor contact?

 

Only way to prevent this would be to lower the current draw by replacing the signal bulbs with LEDs.

 

I pulled the number 4 fuse out and it was plastic welded from behind. There was nearly a volt voltage drop over the fuse and lots of heat. The fuse box looked nasty and after pulling the fuse box back I could see that the insulation on the Y/r power wire for for the fuse #4 ignition circuit was melted some too. After studying the wiring diagram for a while I found that right next door to the #4 fuse is the #3 fuse which provides a dedicated circuit for a rear window defogger option that my truck is not equipped with. Since this circuit was serving no purpose I snipped the #3 yellow wire about 12" out from the fuse box and cut the Y/r wire from the #4 fuse right at the fuse terminal. After cleaning up the melted portion of the Y/r wire I spliced the #3 yellow wire from the fuse box to the harness end of the Y/r wire. Every thing is working properly now. Thanks once again for pointing me in the right direction.