Somebody that actually knows something about cars!!!!!!!!

Question

have a 1992 Dodge w-250. it has a cummins, 5 spped, 4 wheel drive. something funny is going on with the electrical stuff. the speedometer does not work and the fuel guage dosent. i replaced the speed sensor and checked to make sure that the speedometer was getting power with a volt meter. everything seems to be good. i pulled out the little gear that the speed sensor connects to and it working properly. im stumpped.

The fuel guage!

the low fuel light will come on when im low on fuel but the guage dosent work. when i fill up the tank it reads full but 5 min later down the road it reads empty. maybe the float is messed up?

also i had to replace the alternator and put a internol regulator on it because it wont work without it. i dont know if that has something to do with the speedometer or not. and the lights wont come on the ac switches. the blower and everything still works but the lights wont shine! i don know if that is significant to the problems... but im stumped!!

there isnt a speedo cable. its electronic. all the fuses are good every where. i have been trying to figure this out for about 8 months now and i need fresh new ideas. im looking for answers that a vary good mechanic might, just might know!!!!

Answer 1

the only thing that i can think of right off is maybe the ground wire is causing problems on it ,theres a lot of ground wires on that one,and the body has to ground really good to the frame if it doesnt they will do this,once in a while they will make ground through certain switches and make things work for a short period of time,and other times they wont,id check all the ground wires really good,good luck.

Answer 2

it sounds like the guage cluster has gone bad.  

Answer 3

yea guage cluster and your gas guage is the sending unit. replace the sending unit and guage cluster.

Answer 4

I'm not sure about your particular truck,but earlier Mopars used a solid state voltage regulator mounted to the instrument panel.It's function is to keep an unchanging voltage to any instruments as the battery voltage fluctuates.If it acted out,the fuel gauge would do wierd things and possibly the speedo.

Answer 5

you want somebody on here that knows about cars. well you won't find to many.  most people on here just put down anything and think they know everything so good luck with that

Answer 6

the problems may be actually all part of the fuel gauge issue! the float in the tank has low voltage operating it but if it should be going to short, it could be affecting the dash cluster (all gauges etc) at 1st glance I thought to say its a bad ground to the cluster, but your fuel gauge statement gave me pause to think about it more. have you installed any other electrical stuff than the alternator? Have you towed anything that you remember prior to all the crud happening?  

Answer 7

For things to work electrically, it needs a positive and a negative(or ground)  Sounds to me that you don't have a good ground wire.  Run a separate lead from the speedometer holding bracket(if it is metal) directly to the negative post and see if that corrects the problem.  Same applies to the fuel  Guage.  The black or brown wire is normally ground.   Same goes for AC