I have a 93 F350 with a 460 cu in engine gas. Last year the oil pressure guage stopped working. I changed the sending unit several times with no change. So I know there is nothing I can do about that. I had installed these new LED bulbs in the cluster so I am wondering if that could be part of the issue ??? When I put the LED bulbs in all the sockets I noticed that there is a Red battery light on the bottom of the cluster that just stays on all the time. Don't know what this is telling me. . Yesterday I noticed the voltage guage would just go up to 8 and stay there. I put a new battery in in June and check the voltage today and it is fully charged. Today I started the engine and then disconnected the battery to see if the alternator was putting out enough to run the engine. It kept running. so I figure the alternator is good. Any advise ???? Thanks.. Fred z

 

 

When I swapped a tach cluster in, my voltage gauge was reading low... turned out it was just sticky. If I went over a railroad crossing or speed bump it would jump to normal, I could simulate that by smacking the top of the dash.

 

Never disconnect the battery while it is running!!!
This can send a voltage spike to over 100 volts.
These newer trucks (OBS) have electronic devices can be messed up.
Your lucky if did not mess up the PCM, radio and other sensors.
Only time will tell as now you may have other problems down the road from doing this.

 

You must put back in the incandescent lamp for the charge indicator or you will not have the alternator charging!! On most clusters there is also a 560ohm(??) resistor across that lamp to allow the charging ckt to work if ever that lamp burns out. That usually is part of the lamp socket.

Get a real meter and check at the battery with engine running. These gauges are mostly fancy idiot lights and are not accurate .

 

 

Thanks 4Trrucks,, Thanks for being the first to reply to my post and giving me some good advise. Strolling down memory lane looking at one of my old posts. I guess I didn't update my post since nobody commented on it and I have had many coolant and braking issues with this truck since I purchased it in 2002. The overheating issue in 2013 turned out to be a freeze plug. After taking the truck to two different mechanic for the replacement of the freeze plugs neither one was able to replace the ones behind the motor mounts and didn't want to pay the thousands of dollars they wanted to remove the engine to get to them. I just kept bottles of Bars Leak handy. Then when the transmission had to be rebuilt I realized that they should be able to jack the engine up enough to remove those motor mounts and get to those freeze plugs. What am I going to do with those bottles of Bars Leak now?
The ABS light turned out to be the ABS modulator valve. My F350 is a heavy truck and when I breaks down my AAA membership won't tow it so I have to pay a private tow company,$$$,, so I do check under the hood quite a bit. The first two oil sending units didn't look exactly like the one to took out and I thought the first one could have just malfunctioned. and the third one from a different parts store did look like the original one yet still the gauge didn't move. Just a logical process of elimination. So now I know how to check the oil gauge and wiring. thanks.
As for the alternator check method... Decades ago a heard this was how to see if the engine was running off the battery alone. I did make sure I turned the engine off before reconnecting the terminals. Thus avoiding a voltage spike. Thanks again for following up on this post. Fredz