Rear Lights out, but a knock brings it back???

Devil's Advocate · 04-26-2007, 03:00 PM

Both the passenger and driver's side rear lights have gone out. Not at the same time.
Not unusual
What is unusual is that if I tap on the outside of the lense the lights go back on!!!!!
I have checked the connections on the inside and none appears loose.

I have added a trailer hitch wiring kit, from the Toyota camry so all the connections are toyota compatable.

Anyone else have this issue?

It has to be a loose wire, probably a ground, but I have checked and not found a loose one.

bobc · 04-26-2007, 04:48 PM

Hmm, That's a good one. I would have said a loose ground. And since it's on both sides and not the ground, maybe you have a bad trailer hitch module? I'm assuming you checked the ground coming off of the module, too...

Have you had the wiring kit in for awhile? It may be worthwhile to check it with a volt meter (or even a 12v light) to see that it's operating as expected.. In the trailer wiring harness, the running lights goes to the trailer through the wire that is right next to the ground. Sorry, can't remember what color that is.

Looking at the Prius wiring diagram, the brown wires that feed the tail lights run uninterrupted all the way from the junction box that holds the fuse.... It's gotta be something out back between the brown wires coming in on the fuse side of trailer wiring harness to ground which is the bolt on the inboard side of the bumper.... I'm sure you saw this one when you put the wiring harness in. It's also shown on EVnut's site as this is what he grounded his module to.

Good luck,

**efusco** · 04-26-2007, 05:14 PM

Sure, this is covered in the owners manual.....

Ah, ok, maybe not. Weird. I agree, see if disconnecting the hitch module eliminates the problem. And, even if the connections are compatible do you have a tap that could be making an intermittent connection? Odd that it affects both sides though....weird.

c4 · 04-26-2007, 05:16 PM

Definitely check the ground connections.. I had an old Tercel where the dealer would always call me to tell me that I had bulbs out (and that they'd be happy to replace them for me at $10 a bulb and $25 labour).. I always turned them down, then went home and tightened the ground wire nut in the tail light assembly, and the lights would be fine.. I had the same problem in a Corolla and it was always the dealer who "found" this condition, so I suspect that they deliberately loosened the ground nuts every time..

dmckinstry · 04-26-2007, 07:14 PM

<div class='quotetop'>QUOTE(efusco @ Apr 26 2007, 02:14 PM) [snapback]430769[/snapback]</div>

Quote:

Sure, this is covered in the owners manual.....
Ah, ok, maybe not. Weird. I agree, see if disconnecting the hitch module eliminates the problem. And, even if the connections are compatible do you have a tap that could be making an intermittent connection? Odd that it affects both sides though....weird.
[/b]

A tap with an intermittent connection is a definite possibility. I've been having flakiness problems with my CAN-View, and finally confirmed that the problem was with the 12V tap. I changed to a different 12V source (in the center console), and it went from not working at all (that and the NAV) to working perfectly (keeping fingers and eyes crossed).

Dave M.

Skwyre7 · 04-27-2007, 08:24 AM

I had this problem on the driver's rear light. I had the dealership take a look at it while getting an oil change a while back. They said it was a faulty light. I don't remember what they actually said because it was about 3 months ago (maybe more). The end result was me paying about $40 to get a new light. I think they just replaced the LEDs. No problems since. I didn't complain about it too much since I had about 50k on the car already.

alexstarfire · 04-27-2007, 05:45 PM

It could be like the problem I had on my Isuzu. Never found the exact cause, but since replacing the lights fixed it I'm sure it was something inside the bulb itself. At first a tap would get it working, then I had to hit it harder and harder, till it finally just stopped working.

aaf709 · 04-27-2007, 07:18 PM

My first car was a 1967 Mercedes diesel with a taillight problem. It was because the exhaust would enter the light assembly and corrode the connections. It got so I could aways tell a diesel on another Mercedes because the taillight was dimmer on the side where the exhaust was. I ended up making a new ground to fix that problem.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Has anyone disconnected their door and rear lights?	zenMachine	Gen II Prius Care, Maintenance and Troubleshooting	0	08-08-2007 11:32 AM
Prius Always-on lights, fog lights and rear hatch openers	bogeybob513	Gen II Prius Main Forum	8	10-23-2006 05:13 PM
Rear fog lights?	petteri	International Owners	15	10-13-2006 12:47 PM
Rear fog lights...?	pearsonrj	Gen II Prius Main Forum	4	11-29-2005 06:15 PM
Pictures of rear fog lights	richard_durant	International Owners	6	03-03-2004 03:26 AM

04-26-2007, 03:00 PM	#1
Devil's Advocate Senior Member Join Date: Mar 2005 Location: Las Vegas, Nevada Posts: 913 My Car: 2005 Prius Model: Package: #9 Thanks: 0 Thanked 1 Time in 1 Post Friends: 0	Both the passenger and driver's side rear lights have gone out. Not at the same time. Not unusual What is unusual is that if I tap on the outside of the lense the lights go back on!!!!! I have checked the connections on the inside and none appears loose. I have added a trailer hitch wiring kit, from the Toyota camry so all the connections are toyota compatable. Anyone else have this issue? It has to be a loose wire, probably a ground, but I have checked and not found a loose one.

04-26-2007, 04:48 PM	#2
bobc Senior Member Join Date: Jan 2005 Location: Durham, NH Posts: 360 My Car: Model: Package: Thanks: 0 Thanked 1 Time in 1 Post Friends: 0	Hmm, That's a good one. I would have said a loose ground. And since it's on both sides and not the ground, maybe you have a bad trailer hitch module? I'm assuming you checked the ground coming off of the module, too... Have you had the wiring kit in for awhile? It may be worthwhile to check it with a volt meter (or even a 12v light) to see that it's operating as expected.. In the trailer wiring harness, the running lights goes to the trailer through the wire that is right next to the ground. Sorry, can't remember what color that is. Looking at the Prius wiring diagram, the brown wires that feed the tail lights run uninterrupted all the way from the junction box that holds the fuse.... It's gotta be something out back between the brown wires coming in on the fuse side of trailer wiring harness to ground which is the bolt on the inboard side of the bumper.... I'm sure you saw this one when you put the wiring harness in. It's also shown on EVnut's site as this is what he grounded his module to. Good luck,

04-26-2007, 05:14 PM	#3
efusco Troll Slayer Join Date: Nov 2003 Location: Nixa, MO Posts: 17,254 My Car: 2004 Prius Model: Package: #9 Thanks: 50 Thanked 262 Times in 157 Posts Friends: 37	Sure, this is covered in the owners manual..... Ah, ok, maybe not. Weird. I agree, see if disconnecting the hitch module eliminates the problem. And, even if the connections are compatible do you have a tap that could be making an intermittent connection? Odd that it affects both sides though....weird.

04-26-2007, 05:16 PM	#4
c4 Senior Member Join Date: Mar 2005 Posts: 524 My Car: Model: Package: Thanks: 0 Thanked 0 Times in 0 Posts Friends: 0	Definitely check the ground connections.. I had an old Tercel where the dealer would always call me to tell me that I had bulbs out (and that they'd be happy to replace them for me at $10 a bulb and $25 labour).. I always turned them down, then went home and tightened the ground wire nut in the tail light assembly, and the lights would be fine.. I had the same problem in a Corolla and it was always the dealer who "found" this condition, so I suspect that they deliberately loosened the ground nuts every time..

04-27-2007, 08:24 AM	#6
Skwyre7 What's the catch? Join Date: Apr 2006 Location: Richmond, Virginia Posts: 2,332 My Car: Other Non-Hybrid Model: Package: N/A Thanks: 0 Thanked 1 Time in 1 Post Friends: 2	I had this problem on the driver's rear light. I had the dealership take a look at it while getting an oil change a while back. They said it was a faulty light. I don't remember what they actually said because it was about 3 months ago (maybe more). The end result was me paying about $40 to get a new light. I think they just replaced the LEDs. No problems since. I didn't complain about it too much since I had about 50k on the car already.

04-27-2007, 05:45 PM	#7
alexstarfire Join Date: Feb 2007 Posts: 218 My Car: Model: Package: Thanks: 0 Thanked 0 Times in 0 Posts Friends: 0	It could be like the problem I had on my Isuzu. Never found the exact cause, but since replacing the lights fixed it I'm sure it was something inside the bulb itself. At first a tap would get it working, then I had to hit it harder and harder, till it finally just stopped working.

04-27-2007, 07:18 PM	#8
aaf709 Ravenpaw of ThunderClan Join Date: Apr 2005 Location: San Diego, CA Posts: 3,839 My Car: 2005 Prius Model: Package: #6 Thanks: 0 Thanked 0 Times in 0 Posts Friends: 0	My first car was a 1967 Mercedes diesel with a taillight problem. It was because the exhaust would enter the light assembly and corrode the connections. It got so I could aways tell a diesel on another Mercedes because the taillight was dimmer on the side where the exhaust was. I ended up making a new ground to fix that problem.