Electrical problem in lights - The 1947 - Present Chevrolet & GMC Truck Message Board Network

ed455 · 12-30-2004, 09:10 PM

Just rewired the truck with an EZ wiring harness. I did a lot of changes simultaneously. Van column, new harness, new lights, etc., so I don't know the extent of any pre-existing electrical gremlins.

So far the only problem I have encountered is in the lights. With the headlights and parking lights off, the brake lights and turn signals work great. With the headlights and/or parking lights on I'm getting some current backfeed throught the system when the RIGHT side turn signal is on. Symptoms:

1. the turn signal indicator on the dash blinks but does so slowly and the indicator (led) never goes completely out.

2. The rear RIGHT SIDE turn signal goes COMPLETELY out when blinking and does so in OPPOSITE sync with the front (which acts normal).

3. I get some dim flashing of the LEFT rear signal when the right trun signal is on WITH the parking and/or headlights.

The left front and rear parking lights connect to the headlight switch at two different pins according to the EZ Wiring diagram. With the RIGHT turn signal going and the parking lights on, I can unplug the rear parking light wire from the headlight switch and the dash indicator acts the way it is supposed to, but there is still dim flashing of both the rear tail lights.

I have checked for good ground, seems to be OK.

My thoughts: bad headlight switch (original) OR bad turn signal switch.

ed455 · 12-30-2004, 10:07 PM

Think it's my turn signal switch. Everything is hooked up correctly. However, I just discovered that my hazard lights don't work UNLESS I actuate a turn signal. The EZ wiring kit is in GM colors and I have double and triple checked MY wiring job. SInce I have done numerous wiring jobs withou a problem I feel *somewhat* confident in MY ability. I will get a turn signal switch in the morning and see what happens.

Hooter · 12-31-2004, 12:34 AM

hmm, could be a burnt out diode in the turn signal switch, and how is the wiring in your rear harness, I had a problem with my truck in the summer where the signal light would work fine, till Id hit the brake, then theyed quit, turns out it was a Hoppy tralier wiring harness, one of those inline T connectors

ed455 · 12-31-2004, 02:11 AM

The rear harness is just 4 wires. In fact the original factory harness looked like a very long trailer harness. I was not aware that there WAS a diode in the turn signal switch. It does act like a diode malfunction, but I thought the turn signal switch was a simple affair. I will find out in the morning. Oh yeah, it is morning! (1:10 am) Time to quit wrenching and go to bed.

jhow66 · 12-31-2004, 02:12 AM

Try running a jumper wire from bed to frame to check ground. (bed may not be grounded to frame good enough which would cause the problems you are having.)

70c10 · 12-31-2004, 12:41 PM

ed455, I just went thru this same thing with my dads truck and it was the turnsignal switch. While you're in there I would recommend checking the cancel cam, springs and upper steering column bearing. They are cheap and easy to replace while it's apart.

ed455 · 12-31-2004, 07:14 PM

Thanks. I ordered a turn signal switch from Napa today. It should come in Tues.

ed455 · 01-08-2005, 12:20 AM

That was it. I replaced the turn signal switch and the problem is now GONE. One totally rewired truck working perfectly.

12-30-2004, 09:10 PM	#1
ed455 Captain Ed Join Date: Jul 2003 Location: Port Charlotte, FL Posts: 1,241	Electrical problem in lights Just rewired the truck with an EZ wiring harness. I did a lot of changes simultaneously. Van column, new harness, new lights, etc., so I don't know the extent of any pre-existing electrical gremlins. So far the only problem I have encountered is in the lights. With the headlights and parking lights off, the brake lights and turn signals work great. With the headlights and/or parking lights on I'm getting some current backfeed throught the system when the RIGHT side turn signal is on. Symptoms: 1. the turn signal indicator on the dash blinks but does so slowly and the indicator (led) never goes completely out. 2. The rear RIGHT SIDE turn signal goes COMPLETELY out when blinking and does so in OPPOSITE sync with the front (which acts normal). 3. I get some dim flashing of the LEFT rear signal when the right trun signal is on WITH the parking and/or headlights. The left front and rear parking lights connect to the headlight switch at two different pins according to the EZ Wiring diagram. With the RIGHT turn signal going and the parking lights on, I can unplug the rear parking light wire from the headlight switch and the dash indicator acts the way it is supposed to, but there is still dim flashing of both the rear tail lights. I have checked for good ground, seems to be OK. My thoughts: bad headlight switch (original) OR bad turn signal switch.

12-31-2004, 12:34 AM	#3
Hooter My other Love Join Date: Aug 2001 Location: Castlegar B.C. Canada Posts: 4,083	hmm, could be a burnt out diode in the turn signal switch, and how is the wiring in your rear harness, I had a problem with my truck in the summer where the signal light would work fine, till Id hit the brake, then theyed quit, turns out it was a Hoppy tralier wiring harness, one of those inline T connectors __________________ Castlegar B.C.The great white North (Canada Eh!) Hooter_5@hotmail.com First generation Monte Carlo club pictures of my life

12-31-2004, 02:12 AM	#5
jhow66 Registered User Join Date: Jun 2002 Location: Knoxville Tenn. Posts: 3,058	Try running a jumper wire from bed to frame to check ground. (bed may not be grounded to frame good enough which would cause the problems you are having.) __________________ 56 Chevy Bel-Air 2dr. HT (purchased new) 71 Chevy Cheyenne SWB PU (502HO) 65 GMC short bed step--work in progress and my gofer

12-31-2004, 12:41 PM	#6
70c10 67-72 Addict! Join Date: Feb 2002 Location: The TAX State! Posts: 7,857	ed455, I just went thru this same thing with my dads truck and it was the turnsignal switch. While you're in there I would recommend checking the cancel cam, springs and upper steering column bearing. They are cheap and easy to replace while it's apart. __________________ Jim 1970 C/10 Fleetside w/Ghost Flames Lowered 4.5" front and 4" rear (Raked) 355/350 Turbo w/shift kit 10" Redneck Performance Verter w/2500 stall Hooker Super Comps part#2808-1 Performer RPM Air-Gap 12 Bolt w/3:73 gears- Eaton Posi Comp Cams XE262 with 1.6 Crane Energizers, Road Demon 625 and Brodix IK 180 heads

12-30-2004, 10:07 PM	#2
ed455 Captain Ed Join Date: Jul 2003 Location: Port Charlotte, FL Posts: 1,241	Think it's my turn signal switch. Everything is hooked up correctly. However, I just discovered that my hazard lights don't work UNLESS I actuate a turn signal. The EZ wiring kit is in GM colors and I have double and triple checked MY wiring job. SInce I have done numerous wiring jobs withou a problem I feel somewhat confident in MY ability. I will get a turn signal switch in the morning and see what happens.

12-31-2004, 02:11 AM	#4
ed455 Captain Ed Join Date: Jul 2003 Location: Port Charlotte, FL Posts: 1,241	The rear harness is just 4 wires. In fact the original factory harness looked like a very long trailer harness. I was not aware that there WAS a diode in the turn signal switch. It does act like a diode malfunction, but I thought the turn signal switch was a simple affair. I will find out in the morning. Oh yeah, it is morning! (1:10 am) Time to quit wrenching and go to bed.

12-31-2004, 07:14 PM	#7
ed455 Captain Ed Join Date: Jul 2003 Location: Port Charlotte, FL Posts: 1,241	Thanks. I ordered a turn signal switch from Napa today. It should come in Tues.

01-08-2005, 12:20 AM	#8
ed455 Captain Ed Join Date: Jul 2003 Location: Port Charlotte, FL Posts: 1,241	That was it. I replaced the turn signal switch and the problem is now GONE. One totally rewired truck working perfectly.



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