Jump to content

620 Gauge Cluster LED Conversion


Spawn

Recommended Posts

I'm posting this link here, as I don't know if anybody really gets notifications for changes in the How-To section of the Forums.  If an admin or moderator deems that this should not be here, please feel free to remove it.

 

Edited by Spawn
Link to post
  • 2 weeks later...
  • Replies 12
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

Ok, well, either nobody is clicking the picture link to get to the post and comment there, or nobody has the information.  So I'm gonna do my best to try and remove the instrument cluster, but my only concern is with regards to the Wiper Washer switch.  I'm guessing that the knob for the switch pulls off like most other friction fit style knobs, but I'm unsure about the silver ring that rests against the cluster plastic.  It has a groove on each side of the ring, so I'm thinking that you have to use a special tool to remove it (or perhaps a pair of needle nose pliers opened just wide enough will allow me to place the tips of the pliers into each groove and then I can just unscrew it like a regular screw)?


Can anyone who has experience removing the Wiper Washer switch or the Light switch (as I believe it is the same sort of fastening mechanism for it) please let me know exactly how to remove it without wrecking the ring, cluster or switch itself?  Judging from the picture below it seems like the silver ring just screws on over the shaft to hold each of the switches in place, but the ones on my 620 seem to be extremely tight.

001.jpg

Link to post
17 hours ago, datzenmike said:

Pull the switch all the way out and grip the stem as close to the dash as possible, tightly. Now push in on the knob and turn and release, and it comes off.

So it's basically like one of the push and lock style bulbs?  What about for the silver ring with the notches in it?  Any tips or hints on how best to get those removed without wrecking anything?

Link to post

Well, I managed to get the instrument cluster out of the truck... in pieces.1To4i3I.jpg

To be fair, it was already cracked in a few spots, and was fairly brittle.  There was only one screw holding the bezel up just above the tachometer blankoff (but it didn't seem to be holding on to anything as there is no shoulder for the screw to hold against the plastic), and there was the screw holding the bottom of the gauges to the dash frame.  Other than that, the only thing was the wiper washer switch (which came off rather easily after datzenmike provided the information on how to remove the knob - Thanks datzenmike!) and the lighter socket (which I did not figure out was simply a casing screwed on around the socket itself).

Luckily, due to the damage that the instrument bezel had when I got the truck, I had already managed to get a spare bezel (a little lighter in color, but in much better shape), so I cleaned it up and installed the components in it.  Just need to get the LED bulbs now!

BY4uKAP.jpg

  • Thanks 1
Link to post

Well, on my continuing quest to get the gauge cluster converted over to LED bulbs, I made up this image of the rear of the cluster along with each of the bulbs that were removed.  I have marked up where each of the bulbs come from to make it easier for others in the future.  Once I've gotten the replacement LED bulbs figured out, I will edit the image with the appropriate information.

One thing that does have me a little confused/stumped is that for the images that I have seen of other gauge clusters is that I have an additional box or module of some sort on the rear of the speedometer, just to the side of where the cable gets fastened onto the speedometer.  Also, I have two wires with bullet style connectors that I didn't unplug when removing the gauge cluster, one blue and one green.  I've looked into the cavity where the cluster gets installed in the dash, but I only see a blue wire with yellow stripe on it.  I'm not sure if this should be where the blue wire plugs in or not, and for the green wire I haven't found a male opposite for this to tie in to.  Due to the fact that I didn't have to unplug either of these wires when removing the cluster, I'm not even sure if either of these wires should be plugged into anything at all!  The only thing that I can think the box/module might be for is to reduce oscillations in the speedometer gauge needle.  If anybody happens to know what the module is for, I would love to know, as it seems to me that without having the green wire from the module plugged in I don't think that the module is getting a ground (as green is typically used for indicating grounds in wiring).  As for the blue wire, I can't tell exactly where it goes to, as it's just coming out of a grommet hole on the top of the gauge cluster in between the two gauges.

b7SjHzd.jpg

Edited by Spawn
  • Thanks 1
Link to post

That module MAY be an overspeed indicator. There was one of those on a speedo I bought out of Canada. Lights up a light when you go too fast. Unused in my dash now because I don't have the corresponding light.

  • Like 1
Link to post
  • 1 year later...
On 12/14/2018 at 12:01 AM, Spawn said:

Well, on my continuing quest to get the gauge cluster converted over to LED bulbs, I made up this image of the rear of the cluster along with each of the bulbs that were removed.  I have marked up where each of the bulbs come from to make it easier for others in the future.  Once I've gotten the replacement LED bulbs figured out, I will edit the image with the appropriate information.

One thing that does have me a little confused/stumped is that for the images that I have seen of other gauge clusters is that I have an additional box or module of some sort on the rear of the speedometer, just to the side of where the cable gets fastened onto the speedometer.  Also, I have two wires with bullet style connectors that I didn't unplug when removing the gauge cluster, one blue and one green.  I've looked into the cavity where the cluster gets installed in the dash, but I only see a blue wire with yellow stripe on it.  I'm not sure if this should be where the blue wire plugs in or not, and for the green wire I haven't found a male opposite for this to tie in to.  Due to the fact that I didn't have to unplug either of these wires when removing the cluster, I'm not even sure if either of these wires should be plugged into anything at all!  The only thing that I can think the box/module might be for is to reduce oscillations in the speedometer gauge needle.  If anybody happens to know what the module is for, I would love to know, as it seems to me that without having the green wire from the module plugged in I don't think that the module is getting a ground (as green is typically used for indicating grounds in wiring).  As for the blue wire, I can't tell exactly where it goes to, as it's just coming out of a grommet hole on the top of the gauge cluster in between the two gauges.

b7SjHzd.jpg

I have the same question... What is that box for?!  I took the front off the Speedometer and the Red wire connects to a screw beside the Odometer, but I can't tell whatfer either..  I have a 73 620 and mine looks just like yours. How'd the LED conversion go for you?

Link to post

You'll note that the speedometer does not go down to 0 but stops at 10. There is a switch that I believe grounds the BCDD to reset it. My B210 had the same thing and you may have noticed that when slowing down in 1st gear when the speedometer touches the 10 the engine suddenly drops off? and you have to get the clutch in quickly.

 

The plastic box might be the seat belt warning light and/or relay for a buzzer.

Link to post
  • 1 month later...
On 8/2/2020 at 9:14 PM, Tony620 said:

I have the same question... What is that box for?!  I took the front off the Speedometer and the Red wire connects to a screw beside the Odometer, but I can't tell whatfer either..  I have a 73 620 and mine looks just like yours. How'd the LED conversion go for you?

The LED conversion went relatively well, however, I am not getting the warning lights to come on like they used to during startup.  It may be due to the fact that I haven't completely reattached the dash cluster to the dash, or possibly that the LED's I used may be polarity specific.  I did notice that I could get the high beam indicator to flicker depending on the position I put the dash cluster into.  I also see a bit of a very faint steady light coming from the right turn signal indicator when not on, but when I do use the turn signal indicator it is quite bright!  I haven't posted an update on all of it, as the project has kind of been sitting on the back burner due to the driver's floor pan rusting out to the point where the cab mount is no longer actually attached to the chassis via the floor pan, so it won't pass inspection.  

I should probably create another post seeing if anyone in around Upstate New York (Capital Region) might happen to have a couple of front fenders, as they have rusted out to the point where they are going to be needing replacing.  New York weather is not extremely kind to older vehicles like the 620!

Link to post

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

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.

Loading...
×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.