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XJS ( X27 ) 1975 - 1996 3.6 4.0 5.3 6.0

XJS Headlights won't flash

 
  #21  
Old 03-15-2019, 12:16 PM
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Originally Posted by kansanbrit View Post
Carsnplanes, thanks for your very detailed explanation. So it sounds that the piece I was missing is that the flash switch is not really the flash switch, it is the dip/main switch that also has a flash function. By the way, I looked at the schematics in a 1990 service manual and it shows a circuit similar to that detailed at the very top of this thread, not the simpler one. I think the Hella device shown in the photo is in fact the headlamp control module shown in that original diagram. So going back to the OP problem, terminal 81a (blue/black) should be grounded by the flash function in the stalk which should then trigger the module to connect the 12v on terminal 30 straight through to terminal 56a (blue/white) high beam output.
Actually your first statement is not entirely true. Early cars that used the on dash rotary headlight switch do not use a "module" that are used on the later cars. The early cars for which we were troubleshooting used a rotary headlight switch where it would pass the 12 V power through it to the lamps rather than control a heavier relay to to do the work. The wire diagram shows this by path described where 12volts works it way through the ON switch to the normally relaxed Hi beam/Low beam relay. This is the same metal relay shown in the red car photo. The only way this relay is energized is with HI beam stalk movement, either momentary towards you or detent away from you. So the job of the early stalks was for HI beam action by energizing the relay for hi beams and low beams when relay is relaxed.
Newer cars (92 -96)use a module with a "flip/Flop circuitry where a momentary pull is high, another pull is back to low. This happens in a rectangular black box mounted on the left side inner wheel arch. The headlight main switch is on a small three position switch on the stalk itself. The module type wiring is on the first wire diagram in this post.
 
  #22  
Old 03-16-2019, 08:31 AM
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Originally Posted by carsnplanes View Post
Actually your first statement is not entirely true. Early cars that used the on dash rotary headlight switch do not use a "module" that are used on the later cars. The early cars for which we were troubleshooting used a rotary headlight switch where it would pass the 12 V power through it to the lamps rather than control a heavier relay to to do the work. The wire diagram shows this by path described where 12volts works it way through the ON switch to the normally relaxed Hi beam/Low beam relay. This is the same metal relay shown in the red car photo. The only way this relay is energized is with HI beam stalk movement, either momentary towards you or detent away from you. So the job of the early stalks was for HI beam action by energizing the relay for hi beams and low beams when relay is relaxed.
Newer cars (92 -96)use a module with a "flip/Flop circuitry where a momentary pull is high, another pull is back to low. This happens in a rectangular black box mounted on the left side inner wheel arch. The headlight main switch is on a small three position switch on the stalk itself. The module type wiring is on the first wire diagram in this post.
Thanks for the clarification. It looks like the circuit i have showing the module, dated '91, is actually for the 92MY.
 
  #23  
Old 03-16-2019, 08:51 AM
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Originally Posted by kansanbrit View Post
Thanks for the clarification. It looks like the circuit i have showing the module, dated '91, is actually for the 92MY.
Ok, so in the case where you have the black larger module, the the momentary stalk pull even with main headlight switch off, happens in the module by applying that momentary ground through the stalk to the module and completing the ground for the high beam only coil to pull. You can see that boxed "4" supplies the power to the high beam lights as well as one side of the coil where it waits for the stalk ground to complete it thus giving you Hi beams during the day with main switch off.
With Main switch ON, 12V power now comes from the switched on "headlight relay" and enters the module and allows the transistor logic flip/flop action of the stalk to control hi beam /low beams that way.
 
  #24  
Old 03-18-2019, 10:14 PM
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Id resolder all of the dry solder joints on any relay or module thats headlight related.
 

Last edited by Brewtech; 03-18-2019 at 10:17 PM.
  #25  
Old 03-19-2019, 04:41 AM
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Originally Posted by Brewtech View Post
Id resolder all of the dry solder joints on any relay or module thats headlight related.
I'd agree with that as my own headlight module in my '95, can be intermittent. It will be on normal beams and if I toggle to Hi beams and back to Low, I lose the lights completely on Low. HI works, but I have to work at it to bring the Low or normal, back on. Somebody on this forum has taken the black module box apart and either cleaned up the contacts or re- flowed the solder joints with good results, which I will also do.
 
  #26  
Old 03-19-2019, 06:36 AM
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It's easy to take apart and resolder. I actually had to change the transistors in mine, as one of them had failed with a short circuit that left the headlights on permanently.
 
  #27  
Old 03-19-2019, 08:04 AM
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Originally Posted by bladerunner919 View Post
It's easy to take apart and resolder. I actually had to change the transistors in mine, as one of them had failed with a short circuit that left the headlights on permanently.
Which relay type did you have that you repaired, the older metal relay shown in the red car or the later Lo/Hi toggle type black plastic module.
 
  #28  
Old 03-19-2019, 08:32 AM
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The later, black one.
 
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Old 03-19-2019, 08:58 AM
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Originally Posted by bladerunner919 View Post
The later, black one.
Alright, thanks. It's now on my to-do list.
 
  #30  
Old 03-19-2019, 09:57 AM
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Cool. They do seem to be a little troublesome and are about 80 to replace. However, the only things that can really go wrong are the capacitor and the transistors, so I replaced all three for a total cost of about 4. Seemed a worthwhile investment!
 
  #31  
Old 03-19-2019, 02:48 PM
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Originally Posted by carsnplanes View Post
I'd agree with that as my own headlight module in my '95, can be intermittent. It will be on normal beams and if I toggle to Hi beams and back to Low, I lose the lights completely on Low. HI works, but I have to work at it to bring the Low or normal, back on. Somebody on this forum has taken the black module box apart and either cleaned up the contacts or re- flowed the solder joints with good results, which I will also do.
I just performed the same thing, and it worked beautifully! Highly recommended!
 
 
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