[HOWTO] CJ7 82-86 Speedometer tear down & gauges tests - JeepForum.com
 
LinkBack Thread Tools
post #1 of 12 Old 02-03-2015, 03:58 AM Thread Starter
stgil
Registered User
1982 CJ7 
 
Join Date: Apr 2010
Location: FRANCE
Posts: 725
[HOWTO] CJ7 82-86 Speedometer tear down & gauges tests

[under construction...]

Hi,!

The Speedometer in is Natural Enviromnent: Jungle wire



As shown LOT of wires!!!...

Here the detail:

The ORANGES wires: dashboard ligths
The GREEN with BLACK stripe wire : LEFT turn signal
The GREEN wire : RIGHT turn signal
The GREY wire: High beam indicator
The MAUVE with WHITE stripe : to Coolant Temperature sender

Coming together:
The RED and BLACK wires : BRAKE indicator
The RED and ORANGE wires : 4WD the indicator
and finally ...
The RED and PINK wires : that goes to the FUEL sender ...

We will try to tame the speedo by extracting from its jungle (all done by hand: no need for special tools except a wrench with 3/8" socket to release the 4 3/8" nuts from the dashboard...)



front view...



To see what was under the hood ... a small screwdriver stroke to 4 edges in order to extract the chrome bezel...



and 2 screws from the top ...





That appear the differents parts counters (BE CAREFULL to the differents Needles: they are no longer protected !!!)



The other side: 192000Km (~120000mi) : the brake in (not sure about the english word) is quite finished



the detail of the instant mechanism speedometer / odometer ...



the other side ... we can see the odometer mechanism ... and the spring of the speed needle ...



back to the other side ... where still located 2 temperature and fuel gauges ...



We return the beast ... (ACHTUNG! of the Needles) to see in detail the connections ..



side fuel gauge (note the different labels ...)



temperature gauge side ...



Unscrewing all these screws with a 3/8 "socket ...

EDIT: John Strenk says (aka "CJ7 electric Guru" ):

"to be very careful if the threads are rusty when taking the nuts off here

If you put on too much force you can break the board and cause the regulator to be loose and/or short out.

I've seen them twisted around inside before.
"









This allows us to remove the 2 inners gauges ... (Carefull: look for the error )



Next episode coming soon , stay tuned!

FYI: This speedo runs like a charm ... again !

[under construction]


FULL DANA 30 REBUILD->
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
CJ7 LAREDO REBUILD->https://www.jeepforum.com/forum/f8/82-cj7-laredo-diesel-restoration-1179198/
stgil is offline  
Sponsored Links
Advertisement
 
post #2 of 12 Old 02-04-2015, 03:35 AM Thread Starter
stgil
Registered User
1982 CJ7 
 
Join Date: Apr 2010
Location: FRANCE
Posts: 725
Episode #2 (I've added too some comments in the episode #1)

We'll take care to fuel gauge ... with a small screwdriver on the front unclipped it...



GENTLY taken away... DO NOT touch the needle as musch as possible ...



the inner part:



For that matter, will be detailed:



Another detail showing one of the notch to perform the needle setting: in making the move upwards or downwards
one can vary the stroke of the needle ...



The good news is that we are not obliged to open the gauge to be able to adjust ... it is accessible from the outside ...

here the 2 adjustables notches:



Some details of the interior before moving to another gauge ...



the contactor of the bimetallic ...



Turning now to the temperature gauge ...



Which is opened like the previous ...



We see that it is simpler: no voltage regulator ...



But it has the settings notches too...



also accessible from the outside ...



Next episode: the gauge test...stay tuned...

Regards,

Gilles

FULL DANA 30 REBUILD->
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
CJ7 LAREDO REBUILD->https://www.jeepforum.com/forum/f8/82-cj7-laredo-diesel-restoration-1179198/
stgil is offline  
post #3 of 12 Old 02-05-2015, 01:49 AM Thread Starter
stgil
Registered User
1982 CJ7 
 
Join Date: Apr 2010
Location: FRANCE
Posts: 725
Time to test the gauges!

Diagnosis of the fuel gauge:


We make sure we have the following resistances:

S to ground : 68-72 ohms
S to I : 19-21 ohms
S to A : 19-21 ohms
I to A : Zero (0) Ohm
I grounded : 49-51 ohms
A to ground : 49-51 ohms




So that's how the measurements with a multimeter in ohmmeter position:









It is a little high ... but nothing major ...



Always out of range (slightly) ... but since my gauge was working properly, I can only assume that when it does not work
it's not for 1 or 2 Ohms difference.


And it can be explained because I add resistance of the speedometer housing (1 Ohm is very little) may be some
oxydation too ... I think the value would have been correct if I had taken ON the casing of the fuel gauge ...



Temperature gauge diagnosis:

To be on the correct operation of the gauge, we make sure we have the following resistances:

S to A 19-21 ohms





FYI:

I highly recommend to CHECK ALL these values when reassembling the speedometer...
In my case, one of terminal of the gauges was in contact (unintentionally, of course) with the speedometer housing ...
If I had plugged as is: I had to say bye bye gauges! and maybe speedometer too...

To be continued ... stay tuned : next episode (hope last) : bimetal / voltage regulator (High ) technology !

@ John Strenk: if you want to comment, this post is yours!!!

Regards,

Gilles

FULL DANA 30 REBUILD->
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
CJ7 LAREDO REBUILD->https://www.jeepforum.com/forum/f8/82-cj7-laredo-diesel-restoration-1179198/
stgil is offline  
 
post #4 of 12 Old 02-05-2015, 02:55 AM
John Strenk
Moderator
 
John Strenk's Avatar
1976 CJ5 
 
Join Date: Feb 2005
Location: Shalersville Ohio
Posts: 20,164
You are doing great! Keep it up!

But it's not a voltage regulator. More of a Pulse Width Modulated Current limiter.
Back in the day, most mechanics were lucky to have an analog voltmeter nothing fancy like an o-scope, The pulses just fast enough to move an analog meter to around 5 volts so if the mechanic saw 5 volts on his meter he knows the regulator was working. Fast DVM's today can actually resolve the 12 volt pulses coming from the regulator. They can also tell you the duty cycle.

One neat thing about these gauges and the regulator is that they are not sensitive to polarity meaning they work with negative ground or positive ground systems. The also automatically adjust or changes in temperature to keep the gauges in calibration. They work with any voltage from 6 volts to 24 volts, maybe even 48 volts but I haven't tested them that high yet.
And they are impervious to EMP bursts....


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.



To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


I drive a Prius to save money and buy more Jeep Parts....
John Strenk is offline  
post #5 of 12 Old 02-05-2015, 03:07 AM Thread Starter
stgil
Registered User
1982 CJ7 
 
Join Date: Apr 2010
Location: FRANCE
Posts: 725
Quote:
Originally Posted by John Strenk View Post
You are doing great! Keep it up!

But it's not a voltage regulator. More of a Pulse Width Modulated Current limiter.
Back in the day, most mechanics were lucky to have an analog voltmeter nothing fancy like an o-scope, The pulses just fast enough to move an analog meter to around 5 volts so if the mechanic saw 5 volts on his meter he knows the regulator was working. Fast DVM's today can actually resolve the 12 volt pulses coming from the regulator. They can also tell you the duty cycle.

One neat thing about these gauges and the regulator is that they are not sensitive to polarity meaning they work with negative ground or positive ground systems. The also automatically adjust or changes in temperature to keep the gauges in calibration. They work with any voltage from 6 volts to 24 volts, maybe even 48 volts but I haven't tested them that high yet.
And they are impervious to EMP bursts....
Hello John,

They talk about "Regulateur de Voltage" in the French FSM... But I agree it's PWM !

You're right:
They talk about "Voltage regulator" because the local FSM ask to mechanics to test the Voltage on the terminals with
a multimeter (quite easy to found instead a oscilloscop, in a workshop ) in AC Voltmeter mode :
you may read ~5V instead of 12V: => Voltage Regulator, for a mechanic

And I agree too: this technology is simple/tough (EMP Nuke Proof for sure (But I don't think it's your main concern in this case )), reliable and quite indescructible IF understood and checked...
Not sure that nowadays fuel/temp gauges cars will work in 30+ years like this one...

Regards,

Gilles

FULL DANA 30 REBUILD->
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
CJ7 LAREDO REBUILD->https://www.jeepforum.com/forum/f8/82-cj7-laredo-diesel-restoration-1179198/
stgil is offline  
post #6 of 12 Old 02-05-2015, 08:55 AM
wm69
Registered User
1985 CJ7 
 
Join Date: Jun 2003
Posts: 4,208
How does one adjust the sweep of the needle using the slots on the back of the gauge?

Dad's Scrambler reads 3/4 tank when full, and has since they day he brought it home from the dealership.

85 CJ7 258, borla header, Team Rush, MC2100 ,optima batt, Warn 8274, agr super box 2 & pump, T5 w/ B&M shifter, centerforce 2, superior 1 piece axles, warn hubs 2.5 in lift, 31" BFG MT

85 CJ7 258, A/C, T176, MC2100, Team Rush, Warn XD8000i, superwinch hubs, 3in lift 31" BFG AT/KO
wm69 is offline  
post #7 of 12 Old 02-05-2015, 09:06 AM Thread Starter
stgil
Registered User
1982 CJ7 
 
Join Date: Apr 2010
Location: FRANCE
Posts: 725
Quote:
Originally Posted by wm69 View Post
How does one adjust the sweep of the needle using the slots on the back of the gauge?

Dad's Scrambler reads 3/4 tank when full, and has since they day he brought it home from the dealership.
Hello,

>>> This way <<< Please



Regards,

Gilles

FULL DANA 30 REBUILD->
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
CJ7 LAREDO REBUILD->https://www.jeepforum.com/forum/f8/82-cj7-laredo-diesel-restoration-1179198/
stgil is offline  
post #8 of 12 Old 02-05-2015, 09:46 AM
Dborns
Registered User
1984 CJ7 
 
Join Date: Jan 2010
Location: Kansas City
Posts: 2,543
Awesome write-up, thanks Gilles. I have a speedo in my box of parts that I dont know the working condition of. This will help me troubleshoot any issues.
Dborns is offline  
post #9 of 12 Old 02-05-2015, 09:55 AM
Blutarsky
Registered User
 
Blutarsky's Avatar
1982 CJ7 
 
Join Date: May 2013
Location: Lubbock
Posts: 383
If we have an old speedo, can we do these tests or others to determine if it is good or not without opening and disassembling it?

1982 CJ-7
My build thread ruined by the fine folks at photobucket, repaired by a lot of tedious hours.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Blutarsky is offline  
post #10 of 12 Old 02-05-2015, 10:00 AM
John Strenk
Moderator
 
John Strenk's Avatar
1976 CJ5 
 
Join Date: Feb 2005
Location: Shalersville Ohio
Posts: 20,164
Quote:
Originally Posted by Blutarsky View Post
If we have an old speedo, can we do these tests or others to determine if it is good or not without opening and disassembling it?
Yes,
There are some links in my sig that should help you.
Stgil is just going over everything in the speedo.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.



To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


I drive a Prius to save money and buy more Jeep Parts....
John Strenk is offline  
post #11 of 12 Old 02-06-2015, 01:05 PM
Blutarsky
Registered User
 
Blutarsky's Avatar
1982 CJ7 
 
Join Date: May 2013
Location: Lubbock
Posts: 383
Quote:
Originally Posted by John Strenk View Post
Yes,
There are some links in my sig that should help you.
Stgil is just going over everything in the speedo.
Thank you, I don't want to derail the thread, could you perhaps PM me a recommended meter for a noobie?

1982 CJ-7
My build thread ruined by the fine folks at photobucket, repaired by a lot of tedious hours.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Blutarsky is offline  
post #12 of 12 Old Yesterday, 12:01 PM
kuss312
Registered User
1984 CJ7 
 
Join Date: Apr 2019
Location: Los Angeles
Posts: 1
Very helpful thanks for taking the time to write and photograph!
kuss312 is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the JeepForum.com forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid e-mail address for yourself.



Email Address:
OR

Log-in











Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome