Hi guys , I need some advice on going through an instrument cluster for a Dodge truck . If misses the cutoff by a few years so I won’t mention the exact year,,,,,but I’m ***uming these are very comparable to earlier models . Since it’s a Dodge,,,,,,is there any specific ohm readings to look out for ? It has oil pressure,,,temperature,,fuel,,and charging,,,,amps I’m ***uming ? This is an unknown cluster that I purchased recently for my son,,,it’s his truck . The current instruments in his truck are bad,,,,the temp,,,the amps . The fuel is a little iffy too . The fuel could be a sending unit issue,,,,,it will go down to about half and then won’t move any lower . Here are some pics of what I’m working on,,,,,any direction of where I should look for instructions to go through them and test for operation? I’m planning on cleaning the facings and repainting the needles while I have it apart as well . This is a performance build on his truck,,,,,hot engine,,,,performance ******,,,,,4.10 gear rear end . Thanks for any help you might have . Tommy
I have some experience with those trucks, check the circle of round pins that the harness plugs into, I’ve resolderd many
The little oblong thing that plugs into the circuit board at the back is a voltage reducer. It drops the 12 volt input to 5 volts the gauges like. Just so you know, those gauges were not known to be extremely accurate, the gauges ground through the sending units and poor metal to metal grounds on the sending units have an effect on the accuracy as well. You would need a factory service manual covering the era the gauges are from for testing purposes The speedo places it near the end of the era that used that similar cluster, you need the later version, it covered about a 10 year span pegged on the speedo, if I remember correctly. The fuel tank sending unit is always suspect, but make sure the sending unit has a very good ground, that sending unit ground fixed a lot of fuel gauges.
Clean all connectors, the pins, the points where the gauges connect to the ribbons and the ribbon to sockets for the lights. Read and understand the website mad electrical talking about ammeters. http://madelectrical.com/electricaltech/amp-gauges.shtml Then, check into what gene says about the voltage reducer that lowers the voltage for the oil, temp and fuel gauges and the fuel sender grounding. Make sure the main battery cable and ch***is to body grounds are tight and clean. This appears to have the OE reducer which can be updated to a digital replacement.
My old OT Power Wagon is a few years earlier than the cluster you pictured . As stated the round plug and voltage limiter , can be death to good operations , the firewall plug has , trouble written on it from day 1 of operation also . I got fed up fixing mine , 2 months later another issue . I tossed mine in favor of mechanical gauges in a custom panel . PM I’ll share images of what I did . It’s too late a model to discuss anymore in depth here .
If someone has replaced the fuel sending unit, that could be the problem with the gas gauge. I've owned many late 70's Dodge trucks (and still do), if the sending unit was replace from an auto parts store, they never work correctly. I have three meter minder contraptions on my OT Dodge and Plymouths. Also, see the in the lower left corner of the picture of the back of the cluster, make sure there is wire from that hole beside the letters GRD to a good ground. I hate to state the obvious but many times that is not grounded.
Looks like at least one of the copper tracks has corroded through. You can bridge this by s****ing off the surface laquer off and soldering in a bridging wire. Its a common problem with these flexible circuits. Check the other tracks for continuity.
The amp gauge is close to useless on those.The oil gauge will require an electric pressure sender and will also be inaccurate.. The remaining guages work fine with the correct senders.
The Jalopy Journal
