Jump to content

Recommended Posts

I'm converting my old burned out dash lights to LED lights and was wondering if there's an easy way to test the cluster before installing it to make sure the light bulbs are working okay. I've already installed it once and found some weren't working, and it's a PITA to go back and forth with it. It would be much easier to do if I could hook up a battery and check it first. I tried the link someone posted some time ago and it doesn't pull the video up anymore.

Thanks

  • Like 1
Link to post
Share on other sites

There is a way, but you're likely to cause more damage to the circuit card than it is worth the check for lights.  Use alligator clips for the blue/red wire lead and the ground lead.  The pins vary from standard dash cluster to tach dash cluster.

Let me check your shorts!

http://midlifeharness.com

cactus.jpg.92e5d9d8700abc0ed60c8ccb3426248e.jpg

 

Link to post
Share on other sites

I don't see any wires on the cluster once it's removed. It didn't have the tach originally. I thought maybe a person could use a battery to check by touching off on the copper runs in the circuit board?

Link to post
Share on other sites

One tiny  job in my life is designing test equipment - surely a jig  can be made that delivers the electrical values and simulated signals that the dash cluster requires.? 

sig2.jpg

Enjoy's searching out 71-73 history

Link to post
Share on other sites

20160929_171923_edit2_small.jpg

 

1971 M-Code Mach 1 w/Ram Air, 408 stroker, 285/291 0.558" roller cam, Blue Thunder intake, TKO600, Hooker headers with electric cut-offs, FiTech EFI w/ RobBMC PowerSurge pump

Strange center section with Truetrac, 3.5 gear and 31 spline axles, 4-wheel disc brakes

Link to post
Share on other sites
Posted (edited)

It wouldn't take much to build one. The easiest would be to have the connectors, otherwise you would need to build a spring loaded plug that makes contact with the ribbons, or use alligator clips to connect to each gauge, you would need a 5 volt power source and 10, 40, and 70 ohm resistors. By starting the test at the connectors you would also be testing the circuit board at the same time.

Edit, or buy the tester that Tony linked.

Edited by Don C

 

 

“If you can't explain it simply, you don't understand it well enough.”

--Albert Einstein

 

Link to post
Share on other sites

That tester is great, but is useful only for the oil, water and fuel gauges.  The OP asked about testing his new LED lamps.  I thought about it some more, and there is a way: Find the bulb (1895) that comes from a red molded 2 pin connector.  I believe this is for the heater switch light.  Disconnect the connector and feed +12V to the blue/red wire (female side) and ground to the black pin (male bullet) or to the chassis.  That should energize all of the dash lamps on the circuit.  Probably best to disconnect the headlight switch connector, as I don't know if there would be any feedback issues there. 

  • Like 1

Let me check your shorts!

http://midlifeharness.com

cactus.jpg.92e5d9d8700abc0ed60c8ccb3426248e.jpg

 

Link to post
Share on other sites
Posted (edited)

Just going through a bit of this now. Changed out my gauge cluster to the Hi-Po LED’s, worked great. Then changed out the original AM radio to an AM Cassette I had. Now the 4amp gauge cluster and other lights fuse keeps blowing... I’m wondering if how I hooked up the AM Cassette to the original AM power supply lead is causing the problem? I hooked the main power and the unit ground wire to the plug... When I check with a test light, I don’t seem to have any power at the 4 amp fuse circuit at all now, no matter where the key is turned too.  I haven’t looked at the electrical diagram yet, but, it is something to do with the radio install as that 4 amp light circuit was working fine before I thought I was an electrician... 

Edited by 7173Vert

"Yes dear", has kept me in the hobby a long time...

Link to post
Share on other sites

If you believe the ground line is one of the two leads going to the AM cassette, you're wrong.  The two leads are fused power and fused lamps.  Ground is via the chassis.

Let me check your shorts!

http://midlifeharness.com

cactus.jpg.92e5d9d8700abc0ed60c8ccb3426248e.jpg

 

Link to post
Share on other sites
42 minutes ago, midlife said:

If you believe the ground line is one of the two leads going to the AM cassette, you're wrong.  The two leads are fused power and fused lamps.  Ground is via the chassis.

Yes. Figured that out this morning.... When in a rush, take a step back and think. All good now. Thanks.

"Yes dear", has kept me in the hobby a long time...

Link to post
Share on other sites
10 hours ago, midlife said:

Must not have had your Tim Horton's coffee, eh?

I think I had two by that time... The car has been on the scissor lift for three months now. Just these little jobs left of hooking up some interior pieces to get the car completed and back riding on its own rubber. Just a dumb mistake. The hardest part was finding new 4 amp glass fuses. I had to go to my local store and order one pack of five... Another 24 hr wait for these to come in. Like your sense of humour in any event...

"Yes dear", has kept me in the hobby a long time...

Link to post
Share on other sites

use a new 9 volt battery with wires taped to the terminals     then touch the wires to the  plug aria of the circuit board    you can see the path of the  circuit for the lights  the leds are polar sensitive  the ground runs along the out side of the circuit board  if i remember right 

  • Like 1
Link to post
Share on other sites

Thank you. I did that and it showed me the way. I found the ground terminal first, then the branch running to the lights. Easy to change the polarity of the ones not lit, and I even was able to get the brights indicator and turn signals working while still on the bench. I now have to track and find why I'm not getting power to the positive for the instrument lights at the plug and why my gas gauge isn't working anymore. I thought I may have shorted out the constant voltage regulator so I replaced that again, but still not working. I'm going to check the light switch, but I don't think that would have anything to do with the gas gauge. Always something.

Thanks again everyone. I certainly appreciate the help.

Link to post
Share on other sites

Update to everyone who helped me on these pesky issues: After finding the way to test all of the instrument cluster lights, I was able to get all of the lights working - even the turn signals and bright lights indicator. The problem with them not working when I re-installed the cluster into the dash turned out to be the headlight switch. The gas gauge was another issue. I tried to find a remanufactured gauge, to no avail, so I ended up taking mine apart. I found that there's a very fine wire inside connecting the two terminal posts, and one of them was disconnected, probably when I was removing the nut/washers to replace the circuit board and CVR. I found a window defroster wire repair kit at my local auto parts store and it worked to re-attach the wire, then I added a drop of liquid electrical tape to make sure it didn't come loose again. The dash is back to functional again!

Thanks again to everyone.

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...