1. TheSkunk

    TheSkunk Active Member

    Messages:
    34
    Likes Received:
    3
    Joined:
    Jan 12, 2020
    Location:
    Indiana
    Alright guys been about a week or so now sense I installed my radio and speakers in my 78 Lebaron. Gauges worked like the should after install but all of a sudden my fuel gauge dosnt read above E and my temp gauge is all they way to the left and not moving.

    Does anyone have a good wiring diagram or any clues on what happened? “Bat” gauge to the left of my temp gauge is working and my dash lights work as they should. So I’m kinda confused I reinstalled everything how I found it and now a week later nothin.. also what’s the “best or recommended” service literature on these cars?

    Thanks in advance guys
     
  2. Mikes5thAve

    Mikes5thAve Well-Known Member

    Messages:
    199
    Likes Received:
    59
    Joined:
    Mar 3, 2020
    Location:
    Canada
    The best service literature is the factory service manuals. You can get them on ebay for decent price. That year has 2 manuals so make sure you get both of them. If they're just selling one it's not a complete set.

    Chrysler Plymouth Dodge Electrical and Chassis Body Service Manual 1978 Car | eBay

    For the guages did you have them out or run anything behind that part of the dash? If something was unplugged or a wire pinched or broken that would cause problems. The gauges plug into boards behind them instead of having wires running all over the place but temp and gas are two separate units. There is a little voltage regulator in there that is pretty rare to go bad but can cause problems if it stops working.
     
  3. TheSkunk

    TheSkunk Active Member

    Messages:
    34
    Likes Received:
    3
    Joined:
    Jan 12, 2020
    Location:
    Indiana
    Gotcha only thing I ran behind the cluster was 2 speaker wires. But I made sure they were out of the way of any of the original wiring unless something has come loose? I’ll be pulling the dash back off tonight hopefully and will be able to double/triple check wire routing and such. And thanks I’ll be sure to order them!
     
  4. MoparDan

    MoparDan Well-Known Member

    Messages:
    273
    Likes Received:
    27
    Joined:
    Mar 17, 2011
    Location:
    Daytona Beach, FL
    On mine the temp and alternator gauges weren't working very well, sometimes they'd work other times they wouldn't, I took them out and put them back in and they worked for a little while, then stopped again, after a few times of that I finally notice they seemed loose, turned out the metal plugs (I'm not sure what they're called) the gauges plug into on the circuit board were the problem, I carefully took them off, bent them with pliers, put them back in, then put the gauges back in, and they've worked great ever since. I'm not sure but I believe the gas gauge plugs in the same way as the temp gauge (its been awhile since I had them apart)
     
    Last edited: May 28, 2020
  5. MoparDan

    MoparDan Well-Known Member

    Messages:
    273
    Likes Received:
    27
    Joined:
    Mar 17, 2011
    Location:
    Daytona Beach, FL
    I found this picture online, the metal "plugs" I'm talking about are the 4 matching things in a row 4_Circuit Board_Batt_Temp Gauge Pod Off (2).jpg
     
  6. SRTMirada

    SRTMirada Well-Known Member

    Messages:
    52
    Likes Received:
    29
    Joined:
    Dec 29, 2015
    Location:
    Niagara
    That sardine can looking thing is the voltage regulator.
     
  7. Demonracer

    Demonracer Member

    Messages:
    17
    Likes Received:
    4
    Joined:
    Apr 6, 2012
    Actually it's called a "voltage limiter", it limits the voltage running through the printed circuit panel on the instrument cluster.
     
  8. SRTMirada

    SRTMirada Well-Known Member

    Messages:
    52
    Likes Received:
    29
    Joined:
    Dec 29, 2015
    Location:
    Niagara
    Thanks for pointing that out. I'm getting sloppy in my old age.
     
  9. BudW

    BudW Moderator Staff Member

    Messages:
    4,326
    Likes Received:
    1155
    Joined:
    Mar 4, 2012
    Location:
    Oklahoma City
    The voltage limiter allows 5-volts to your gauges. If you are having problems with both temp and fuel (or oil pressure, if equipped) then the voltage limiter is the most likely suspect. If intermittent gauge operation and/or with the alternator (or amp) gauge, then cleaning the copper contacts make a world of difference.

    Getting off subject a bit, but this link talks about the voltage limiter some RTE limiter - rte . I have two new RTE limiters (one for each car) for whenever I get into the dashes apart on either car. Their limiters are a bit pricey ($50 US) – but are cheaper than getting new gauges if one goes out. Been my experience that factory limiters do go out after ~100k miles or after 20 years – so many of us might be on borrowed time. I had to replace tons of them back when I was working at a dealership (thirty years ago).
    BudW
     
  10. Aspen500

    Aspen500 Well-Known Member

    Messages:
    4,993
    Likes Received:
    1486
    Joined:
    Feb 14, 2015
    Location:
    Rib Mountain (Wausau) WI
    I'm lucky, my car still has the limiter it was built with 41 years ago. There, now I've done it. Next time I drive the car the gauges won't work:eek:
     
  11. Magnum Aspen

    Magnum Aspen Member

    Messages:
    20
    Likes Received:
    7
    Joined:
    Jun 25, 2019
    Location:
    Prescott, Az
    For those who do not want spend the$50 for the regulator from the mentioned company MoparAction Aug 2000 has an article on how to build a voltage regulator from solid state electronics. I did this on my B body and it has been working for 15 years.