Two probably unrelated problems I need help with. My speedo only work intermittantly now kinda jumps around and doesn't work below 40mph. This just started happening Sunday. Now my Od failed. It was "kicking" in and out of od at all speeds since Monday. Checked fluid level and was 1 1/2 qts shy. Topped it off and no change. Now today the od doesn't even engage. I just shut the od switch off and drove it as a 3 speed. This worries me that my trans is about to fail. Could it be my TPS or is it internal in the trans. It's a 93 w-250 CTD a518/205. Has 3.54 gears so not hugely concerned about cruising rpms yet. But I tow an open car trailer frequently. It does need a converter anyways so if the trans needs replaced guess it will be awhile so I can afford both converter and trans.

Where do I start checking? Make a potentiometer? Not sure how to do that either. OD switch fail?

Thanks in advance,Vinny

 

Since you're speedo is jumping also, i'd look real close at the VSS/drive on the tail-shaft of the tranny.

 

If your speedo isn't giving a good steady reading the PCM will drop OD out.

Check that reducer box that screws into the side of your T case. It has been know to cause problems.

 

I've noticed this being quite common in the 4wd's.....Does it happpen to the 2wd's as well? I'm just curious...i seem to be experiencing alot of electrical gremlins lately with my 2wd dually and just wondering if i can expect the same problem....I just rewired in a new headlight switch/connector block, because the connector block was melted, and my stock radio now doesn't work MOST of the time...My window motor that i put in last summer must have gotten wet inside the door, cause it started making noise a few weeks ago, and now doesn't like to work... I'm having a blast with this old POS !!!
Only 97K on it, and nothing wants to work right. I'm seriously thinking about finding a nice old Chevy 1 Ton to put this cummins in...If the **** truck wasn't in such nice shape !!!!!!!! 100 percent rust free original paint !

 

So how do I check it. I am retarded at electrical work. If it's only using a voltmeter I can do it.

I put a potentiometer on it and it still doesn't work.

Kinda at a loss and thinking about trading off my truck. Besides, I wanted a 5-spd anyways........

Vinny

 

The reducer is a mechanical gearbox...

 

Okay, and how do I check it. What am I checking for. Does it have gears inside or something? A little more knowledge please.

Vinny

 

Yes, it has gears. Make sure that it's firmly attached to the transfer case and that the drive stub and socket are not stripped out. Also make sure the VSS is tight.