no headlights

[cgsheen1]

Or remove the relays, get back to stock, troubleshoot the circuit and get the headlights working, then get the relays back in... May have helped to know about modifications from the start.

[Zed Head]

4 hours ago, kenward1000 said:

Replaced both of the headlight relays but still no headlights.  Next will test to see if the connectors that the relays plug into, have battery power and then trigger power when the combo switch is set for headlights.  

No offense but I'm going to guess that you don't feel comfortable doing electrical system diagnosis.  There really should be several voltage measurement reports here.  At the headlight switch (input and exit), at the fuses (left and right), at the headlight sockets, etc.  And at the relay socket pins before you replaced the relays.  That's the way to do it, you shouldn't pull or replace anyhting until you've taken a measurement or probed with a test light.  

You've pulled fuses and replaced parts but haven't reported any actual measurements.  I'd start at the headlight fuses.  They're easy to get to and you can go forward or backward from there.

Measure from each side of the fuse to ground with the headlight switch on. 

[Yarb]

@kenward1000 I agree with @Zed Head can you give us an idea of you’re familiarity with a meter. This will give us an idea of where and how to diagnose. Starting at the source is key. 

Edited June 12, 2024 by Yarb
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[kenward1000]

Not to worry about my electrical and electronic skills.  Me and electrons are tight.  Haven't needed to employ my Tektronix oscilloscope or Fluke amp clamp yet, just using my Fluke DMM's.  Voltages are all good at my aftermarket fuse panel and all the fuses are good.  At the connectors for the previously installed dual headlamp relays, there is zero voltage.  Zero battery voltage at pin 87 and zero voltage at pin 85 on the relays when the combo switch is switched to headlights.  That's why there is no voltage at the headlight connectors themselves.  The issue is somewhere between those relays and the rebuilt combo switch.  I'm working through it methodically.  Appreciate all the suggestions.  

[Terrapin Z]

Those relay kits usually have another in line fuse (blade type) between the battery and the relays. 

 

[kenward1000]

4 hours ago, Terrapin Z said:

Those relay kits usually have another in line fuse (blade type) between the battery and the relays. 

 

Yes there is an extra blade fuse in the ground circuit to the dual relay kit.  It's good.

[Zed Head]

8 hours ago, kenward1000 said:

Zero battery voltage at pin 87 and zero voltage at pin 85 on the relays

What about the pin for pin 30 on the relay?  Might just be a bad connection at the battery supply.

https://www.thezstore.com/product/3861/headlight-relay-upgrade-harness-70-73-240z

 

[kenward1000]

2 hours ago, Zed Head said:

What about the pin for pin 30 on the relay?  Might just be a bad connection at the battery supply.

https://www.thezstore.com/product/3861/headlight-relay-upgrade-harness-70-73-240z

 

Bingo!  Last time my Z was in the shop for a checkup on my Rebello engine, the new wrench decided to replace the battery (which really didn't need replacing). The power cable for the dual headlight relays is black, so the new wrench assumed it went to the negative post on the battery. Moved it back to the positive post and headlights work again. Thanks so much for your help!

It might have helped if the MSA kit had a red power cable or at least a "+" tag on it.

 

 

 

 

Edited June 12, 2024 by kenward1000

[Yarb]

Wrap the very end with Red tape so the next guy doesn’t jack it up 

[kenward1000]

4 minutes ago, Yarb said:

Wrap the very end with Red tape so the next guy doesn’t jack it up 

Used my label maker to create a label saying 'Plus' on both sides. 

Basically the whole process for me went:  Check every last fuse that I could find (both visually and electrically), verify the combo switch is working.  Test the stock headlight filaments for continuity (good), discover zero voltage supplied to the headlights.  Work backwards to the MSA dual headlight relays, replace them, no improvement.  Zed Head posted an image of that same MSA kit where the text said to power it from the positive side of the battery.  Discovered it connected to the negative side, by the tech that had replaced the battery.  All lights working now.

Was there a better troubleshooting sequence to follow?