Need help with my '95 dually. A few days ago I lost my charging system, tach, and ac compressor won't kick in. After searching & reading on here over the weekend, I decided to replace the engine speed sensor. I did, also set the air gap to 49 thousanths and I still have the same problem. Today I pulled the alternator and had it tested, and it's good. I put it back on and still the same problem. I've checked fuses, wires, etc, and haven't found anything wrong. I started it one last time before I quit, and the starter stuck...........by the time I got the battery cable off I think I fried the starter. This may or may not be related to the other problem, I just don't know. If anybody has any ideas on this I sure could use 'em right about now.......Thanks in advance for any replies.
Barry Franklin

 

Try unplugging the computer on the firewall.Spray some contact cleaner in the plug and plug it back in.Sometimes corrosion gets in there and things go crazy.

 

The contacts in the starter are a common wear item and can be replaced and upgraded on the bench.

Starter Contacts from LarryB

After repairing all that, I would check the harness connections near the fire wall and trace the wires to the ESS for any breaks or lost connections. Also a good clean of the grounding harness to the block and cab are never a bad idea.

Sometimes the switch can be worn in the column too and some electrical contact cleaner may remedy it.

 

Barry, also make real sure the fuses are all good, at least on the 97's I believe it is fuse 9 on the PDC.

 

Sorry posted wrong place.

 

Patdaly, are you talking about the fuses out under the hood? And do I have to tear into the steering column to check the ignition switch? I read the three wires that go to the speed sensor with a meter, and with the switch on I got 5 volts, 8.8 volts, and 0 volts......I'm really lost this time. And I really need the truck right now too...............I wonder if I could have got a bad speed sensor?

 

Can anybody tell me how the key cylinder comes out of the steering column? I am going to change the ignition switch and see what happens. I have the steering wheel off, and I'm trying not to bother the clock spring thing or whatever it's called. Any help is appreciated.
Barry Franklin

 

You should be able to just test the switch to see if you are getting the contact there. Even without the key you can just jumper it to see if it starts or if you get juice to the right wires.. I don't have the wiring diagrams in front of me to be certain what wire goes out to the pcm.

 

Looking at the wiring diagram for my 96, you should be able to test the igintion switch at the starter relay. Battery voltage goes from the ignition switch, thru the clutch switch if manual, to pin 86 on the starter relay. Pin 85 on the relay goes to ground. If automatic, pin 85 goes thru the park/neutral switch to ground. Pin 30 on the relay should have contant battery voltage. Pin 87 goes to the starter solenoid. Pin 87A is not used.

When the ignition switch is placed in the start position, battery power goes to pin 86 to pin 85 to ground. This activates the relay. With the relay activated, pin 30 is connected to pin 87 which activates the starter solenoid/starter.

Fuse 9 is located in the fuse panel by the driver door. This fuse provides power to the hold circuit of the fuel solenoid.

BTW, to make these tests you pull the relay out and make the test connections in the relay socket. The pin numbers should be on the relay. There is a test for the relay itself also.

Hope this helps, and good luck.

 

Thanks guys for all the help. I will check things a little more and see what happens.....the truck will start and run, but the charging system, tach, and air conditioning compressor won't work. It's really got me bumfuzzled......

Barry

 

http://dodgeram.org/tech/repair/elect/ign_switch.htm

For some reason the '96 and older key switch is about $30 at Napa while the '97 and newer are over $100.
They are almost exactly the same, but definitely not interchangeable.

Your problems are the classic symptoms of a bad engine speed sensor.
Far as I know the only way to test them is with an oscilloscope. A volt meter will tell you nothing.
The ESS is available at any autoparts store.

 

Yeah, I replaced the speed sensor, but I still have the same problem. Now I have another problem.......I found a blue wire with a fusible link that hooks on the positive post of the battery, and it was coroded pretty bad, so I cut it back to the fusible link and put a new end on it. I left the link, but I had to cut into it some. Now with the wire hooked up, the starter sticks and it won't shut off. If I leave this wire off, it starts and shuts off just fine, and the starter don't stick. What did I do wrong here? I don't know if this is related to my original problem or not. So far I have replaced the engine speed sensor, and the ignition switch, and the starter. I still don't have a tach, air conditioner compressor, and no charging system. And now this problem with the blue fusible link wire. What should I do next?

Barry

 

Check fuel shut down relay maybe stuck check here for wiring diag.

http://www.fostertruck.com/images/st...it_diagram.jpg

Good info here on 12V engine
http://www.fostertruck.com/dodge/starter%20faq.htm
http://www.fostertruck.com/dodge/default.htm

 

Is there any way to check this relay? Mabey with an ohm meter or something?

Barry

 

You don't even need a meter by the sound of your symptoms.
If you turn the key to on without cranking the starter and the shutdown solenoid lifts up it means the relay is stuck on.
Running the engine in this condition for over five minutes will burn up the expensive solenoid and could even start a fire.