Engine/Transmission (1994 - 1998) Electrical Question

[EKlem]

I think that I am having an electrical problem with my truck. When I went to start it, it fired immediately but then died as soon as I stopped cranking. I had a friend crank the truck and verified that the fuel shutdown solenoid was pulling up while cranking but not being held up afterwards. So we tied it up and drove the 2 hours home.



The other sypmtoms that I am getting are that, the alternator isn't charging(verified with voltmeter) and the tach and speedo don't work. I looked at the other thread going on about this sort of problem and with the diagram given, I don't see how these other circuits tie in with the shutdown solenoid.



So my question is, where should I start looking when I try to fix it tomorrow? Do I have multiple unrelated problems or could it all be tied together? I am at school so I don't have a good workplace but I do have a multimeter and basic tools here. Thanks for any help.

 

[Joe G.]

Check your ignition switch. The hold coil is directly connected to the ignition on circuit.



Check your fuses too.

 

[EKlem]

Is there a simple way to check this switch? Unfortunately the only form of a service manual that I have at school is a Haynes and it only describes how to check an ignition switch on a gasser.



I realized that I omitted some information in my original post. When I turned the key to the on position before starting it, the first time everything was normal with the WTS light and all but then, none of those lights came on.



Thanks for the reply Joe.

 

[Howard Durand]

Check fuse #9, it feeds several circuits. The shutdown solenoid hold in coil is one of them. To add to this, protected circuits fed from #9 includes the PCM which may be causing the other problems you are reporting.

 

[McLaughlin]

Might look at this http://users. adelphia.net/~mclaughlin1542/files/truck fuel cutoff.jpg it is a wiring diagram for a 97 fuel cutoff solenoid but may be similar.

 

[EKlem]

Thanks for the suggestions guys. I am going out to work on it in a few minutes. Hopefully it is something simple like a fuse.

 

[CBeeman]

you might want to check your battery cables to make sure everything has a good clean connection

bad cables can cause a soleniod problem and a charging problem

 

[EKlem]

I looked at it and it still isn't running but I have some new info. The number 9(labeled engine) fuse blowing was correct. I replaced it and when I turned the key to the on position, all of the lights acted like they should. However, as soon as I bumped the starter, the fuse would blow. Any ideas on where to look next?

Since I didn't have a 10A fuse, I put in a 15 just to see if that would get it running. It is blowing a 15 so I think that I must have a short somewhere. I just don't know where that is.

 

[JFaughn]

Your starter may be on its way out [ drawing too much current ] , go to a parts house or shop & have the starter & alt. load tested .

 

[EKlem]

Your starter may be on its way out [ drawing too much current ] , go to a parts house or shop & have the starter & alt. load tested .

If my starter is on its way out, will it cause this fuse to blow? I would think that the input to the low current side of the solenoid would still be the same. Please correct me if I am wrong on this.

 

[JFaughn]

When ever your have non spec. volts or amps [ high or low ] your going to have issues .
It may not be the starter , but something in the starter circuit , its all about testing , a load tester is something that you can not get around & is needed for starting / charging systems , and cost too much for an end user , thats way getting tested some where is the way to go ,
Then after that everything after that can be done with a muti meter & test lite .
This should help .

LarryB's Dodge starting problems solved here.

 

[DPapworth]

I have the service manual for a 95. The following assumes the 1996 is the same.

Fuse 9 drives a whole bunch of stuff, including the fuel heater relay, intake air heater relays, the data link connector, the auto trans overdrive solenoid (if present), the fuel "shutdown" solenoid hold coil, the PCM,
the "automatic shutdown relay", the "fuel pump relay", etc.

It has nothing in particular to do with the starter.

I'll hazard a guess based on your symptoms. Since the fuse does not blow immediately, but only when the starter is engaged, I'll guess a possible bad
fuel pump relay, automatic shutdown relay, intake air heater relay, or fuel heater relay. The PCM engages these functions during crank and run, but not with the key on. As soon as you go to crank, the PCM tries to turn on one or more of these relays, and the fuse blows. Once the fuse blows, you have the rest of your symptoms.

I think the relays can be removed or disconnected easily enough, and even when missing the engine should still start. The one that blows the fuse is the bad one.

 

[EKlem]

I have the service manual for a 95. The following assumes the 1996 is the same.



Fuse 9 drives a whole bunch of stuff, including the fuel heater relay, intake air heater relays, the data link connector, the auto trans overdrive solenoid (if present), the fuel "shutdown" solenoid hold coil, the PCM,

the "automatic shutdown relay", the "fuel pump relay", etc.



It has nothing in particular to do with the starter.



I'll hazard a guess based on your symptoms. Since the fuse does not blow immediately, but only when the starter is engaged, I'll guess a possible bad

fuel pump relay, automatic shutdown relay, intake air heater relay, or fuel heater relay. The PCM engages these functions during crank and run, but not with the key on. As soon as you go to crank, the PCM tries to turn on one or more of these relays, and the fuse blows. Once the fuse blows, you have the rest of your symptoms.



I think the relays can be removed or disconnected easily enough, and even when missing the engine should still start. The one that blows the fuse is the bad one.

I was thinking of doing exactly what you said by removing relays and trying to start the truck. Only problem is, I need some more fuses. I will try to do that and start playing with the relays.



Thanks for all of the help guys. It is really nice to have this great group when you are trying to solve a problem in a muddy parking lot while it is raining.

 

[Joe G.]

The fuel pump relay is not connected on the diesel. It's in a dead socket. It can be used as a replacment if needed. The others are certainly suspects. I suspect the fuel heater relay. If it is, then the fuel heater is probably burned up. Anyway, if you don't find that it is a relay, start disconnecting stuff. Especially the harness to the fuel heater. The fuel temp sensor may be burned up.

 

[EKlem]

I am getting closer on it. I unplugged the connector from the fuel shutdown solenoid. I had a friend(member LSchulz) try to start the truck while I manually held up the shutdown solenoid. The truck fired right up and everything worked as it should. So I think that it is now isolated to the shutdown hold up circuit. I don't know whether it is the relay or the solenoid itself. Kind of tempting just to go to a cable shutdown.

 

[Joe G.]

The hold coil is NOT involved with the relay. The relays that are involved with the ignition on circuit are the fuel heater and intake air heater relay. When you start the truck the fuel solenoid relay pulls the fuel solenoid up with the pull up coil. AFTER the truck starts and you let the key back to run the fuel solenoid relay is no longer doing anything. The hold coil is directly connected to the ignition on circuit. No relay. Something else is causeing fuel 9 to blow. The failing hold coil is most probably a symptom of something else failing.

 

[DPapworth]

The "hold up" circuit quits because fuse 9 blows. Fuse 9 blows because some other load turns on turning the start process, and that load is too high.



After studying the schematics some more, the most likely candidate is the "automatic shutdown relay". In the diesel, this relay supplies the field current to the alternator (and that's it). The PCM turns that relay on once the engine starts (spins faster than 475 RPM). It may also turn it on when it senses the starter spinning (carry over from the gasser where the "shutdown relay" also controls other things). Anyway, if the "shutdown relay" coil is shorted, it would blow fuse 9 shortly after the starter is engaged.

 

[JFaughn]

It may be of no relevance , but on my 94 there is a starter relay that could cause something like this .
Thats why I think they keep changing things , once you get something figured out they change .

 

[Joe G.]

The starter solenoid is NOT on fuse 9. There are quite a few things on that fuse that could be the problem. Has the engine been washed or otherwise exposed to water? If so, there may be a wet connection somewhere. If you don't have a wireing diagram here is a list of things on fuse 9: A/C clutch relay, fuel solenoid hold coil, heated air intake relays, fuel heater relay, engine data link connector, transmission overdrive solenoid, transmission torque convertor lockup solenoid. It is also connected to the PCM. The easiest way to find this is to unplug these things one at a time until the fuse quits blowing.

 

[EKlem]

It was raining the day that I started having the problem and the vehicle had been driven before I had the problem so it is possible that water got in somewhere.



I have tried unplugging everything one at a time on fuse 9 and the only thing that stops the fuse from blowing is to unplug the shutdown solenoid. I have started the truck three times this way and not had a problem while the fuse will immediately blow with any other combination. My current plan is to put pick up a pto cable after I get out of class today and put in a manual shutdown. Then I will monitor the situation and see if I start having problems again. Once I get a better place to work, I will look into it a little more but I have exams coming up and don't have a good place to work.



Thanks for all the help that you guys have been.