98 Ram no start

98 Ram stalled and will not start. First I checked the fuses in the fuse block under the hood. It ran for 3 seconds and hasn't since. I first changed the Crank position sensor, no start. I tested the fuel pump, 45 PSI but dropped to 0 in 2 minutes. I swapped it out with a new one. Pressure is 48 and stays there.

My battery is fully charged and I changed the cap,rotor, wires and plugs a month ago. I also changed the coil. There is good gas in the tank. Lawn mower runs on the gas I put in.

I am at my wits end and I can not seem to figure it out. Anything else I can check? Only thing else I can think of is the PCM.

Do you have spark? Is the coil being commanded to fire? Are the injectors being commanded to fire?
Before changing partrs and adding more questions than answers we need some actual testing.

No spark per my spark tester. I have a P1389 code, which is the ASD relay. I swapped the relay a few times with the others on the fuse block. Still no start. Cap and rotor still look good. So am I safe to assume that I may have received a bad crank position sensor, or did I miss testing something else?

Just a dumb question, but have you cleared your computer and try to start it?

Yes, a few times just in case.

We lost 2 ecu's on our 98 but when it happened a code reader wouldnt connect to it.

broken/ corroded wire in the harness. you need to check the powers at the relay. there is a wire that branchs off and goes to a few different components, that connection gets corroded and you loose power to a few different relays and computer. you need to do power and ground checks before throwing more parts at it. relay should have 1 power wire all time and 1 with key on. the computer controls the ground. It has been a while, If I remember correctly the branch is in the harness between the fire wall and battery along the left side inner fender. look for the green powder(corrosion).won't be easy to spot, it is inside the taped harness. Getting an aftermarket Bad part is not that uncommon. a scan tool that is bidirectional can command the coil to fire/spark. if that happens then the wiring is good,

Just fixed that problem on a 95 Dakota...changed pick up coil..coil..crank sensor...kept dying and not wanting to restart..found a youtube video...showed were the wires were...and this dakota has been in the desert all its life and still corrode...runs great again..

Thank you for the info. It is raining and I do not have a garage so if it is clear tomorrow I will be searching for corrosion and running my multi-meter.

So I was finally able to check the crank position sensor connector and I have just over 5 volts going to it but the ohm test on the ground pin gave me a .13 so I assume I have a corroded wire somewhere. I am looking for a wiring schematic for the truck now. I do not see any corrosion anywhere at first look so I am about to start looking in the looms.

'98 if I remember has the coil down by the alternator, ck the coil wire for corrosion.Where are you checking for spark? Also if the truck has a tach a quick check of the crank sensor would show rpm 50-100 even when cranking.

5 volts is normal. all the sensors operate between 0-5 volts. The crank position trigger uses a 5v or 0v signal- as the windows on the flexplate/flywheel pass under the sensor, the voltage goes from 5 to 0 telling the computer that a piston is at TDC. others, like the MAP, TPS, etc. use a varying voltage to articulate a range of values.

.13 ohms in a wire sounds normal. copper wire has resistance and will show some value of resistance on an Ohm test.

If the .13 Ohm test is around normal then I am glad to hear that. I will have to test the coil connections, but I am going to take a break tonight and start again in the morning. I really hope it is just a part, even if it is the computer because I really hate wiring and electronics.

So I went and exchanged the new CPS just in case. I went over all grounds and made them shiny or replaced. Same with power wires that were questionable. I still get the P1389 code, which is the "No ASD Relay Output Voltage At PCM".

I switched relays around. Still no power to coil. My battery charger buzzed and smoked so it is toast now. I am kinda of at a lose now and not sure what else to do. I think I may double check some more wires tomorrow.

https://www.youtube.com/watch?v=mcCs3ynqrOE

I just removed all the tape on those wires from the video and I have nothing like what they showed, but I am not getting any power to the asd relay. I have I think 3 or 4 thicker red wires going to the power box and I am about to check them now with the meter.

OK calm down. The code indicates a problem with the asd relay or its wiring. Since the relay has been changed with no effect, its safe to say it's wiring related. Fortunately the wiring isn't all that complicated.

IIRC theres 4 wires on that relay:
1 Battery power, should be hot at all times
2 Key on power, hot when key on
3 Feed to items that are fed from the relay, things like the fuel pump relay, power for ecm etc.
4 Control for relay, this will be a ground when the ecm is commanding the realy to operate. Should be ground when cranking and for a couple seconds after. If the ecm doesn't see a crank/rpm siginal it will command the relay off (no ground)

A basic test ;light can test these circuits. Obviously 1 terminal in the socket should have power all the time, The 2nd should have power with the key on. Test for these by clipping the test light to battery negative and probing the terminals to see which lights up. Make a sketch and mark em for future reference.

The control circuit is tested by cliping the test light to battery positive, probing the other 2 terminals. One should only light the test light when cranking and like stated will light the test light for a coupe seconds after key release. Add this to your sketch.

The feed wire should theoretically show a ground with the test light connected the same as checking the control circuit. This should be a constant ground.

Check these and report back with what is not working as expected. Then we can narrow down which circuit is out of order.

These are the results of the test:

1. No constant power (no power at all) pin 30
2. No power when key on (no power at all) pin 87
3. Connection to positive on battery then to pin 85 and I get constant light. Ground is good.
4. Connection to positive on battery then to pin 86 and I get light for about 2 seconds after key release.

30 Common feed
85 Coil ground
86 coil battery
87 normal open
87a normal closed

When I checked #3 my cruise control clicked for about 2 seconds and I heard a faint hum for 2 seconds but I could not figure out where the hum came from.

By putting the light into #3 you were effectively providing power to the components that run off the asd relay. The noises are a good sign that that part of the wiring is indeed connected.

The lack of power to either hot terminal at the relay starts to point towards a failed fuse link. These go between the battery and fuse block. Normal test for a fuse link is to pull on it, if it stretches, its burnt.

Follow the positive cable to a point where 5 or 6 wires are spliced to it. Those will likely be the fuse links. Start at the battery. You may have more than 9ne bad link, I don't know if the same one provides power to the asd and ignition switch.

I have 3 set of white and black wires encased in a red protective cover. 1 from the firewall and 2 go under the cab. All of the black wires have been sliced with 20 amp blade links and they connect to the terminal on the distribution block. The positive cable attaches to the same terminal.

One of the white wires from under the cab is spliced into a ground. The other 2 white wires are spliced to each other. All three of the blade links have power, when key is on, per my test light. I did not find any other fusible links.

Take another wire and go from one of the ignition on wires to the terminal that should be hot at the relay. See if the truck will start then.

Pics of what you're seeing? Doesn't sound stock.

It is not stock. They are joined by simple inline connectors. I will update with pics tomorrow after work. I really appreciate the help and advice from everyone.

What I was describing was for my Trailer brake. I did not find a fusible link anywhere from the fuse block to the Power distribution center or to the battery. Someone also installed an automatic starter that never really worked and they did an ok job but damn there are alot of wires under that dash now. I did unplug the inline engine connector in the PDC and used contact cleaner and dielectric grease but the bolt is stripped. It seems tight but not like I would like. Still no start. I am leery about using a jump wire from power to the asd relay until I find out why it is not working.

circuit #86 of the relay is key on power and is fused first possibly fuse #9??. turn key on should have power in and out of fuse to circuit 86 of the relay. This lg/bk wire goes to asd relay,fuel pump relay, and 2 different spots to the PCM. ( this is the wire that i have fixed numerous times)
circuit 30 of the asd relay is power all times, it is also fused. 30 amp fuse location #6. this comes out of circuit 87 of the relay and goes to injectors and coil?, dg/or wire.

I jumped power from the positive cable to #86 and still does not start. I messed up my shoulder today and I work late tomorrow so I am done for the night but back @ it in the morning.

I feel like an idiot. I jumped the wrong terminal. I got it to run when I jumped power to #87. Now I need to know how to fix the circuit 30 wire.

Asd feed supply. If you have voltage at the fuse then you have a bad PDC. If so pull it up and figure how you can wire from fuse to the #30 terminal of the relay.

I have a 30 amp blade type inline fuse. Do you think I could splice from one of the other power wires that goes to another fuse or at least go to the battery + cable?

Are you saying the fuse is good? If yes ck the thermial that the fuse goes into to see if it is spread and not making contrat. For testing yes,but for a proper repair it's best tto find the problem. ASD relay drives a lot of things.

The 30A fuse has power to it but not to the asd. That is why I thought maybe just putting an inline fuse from another power wire to the ASD would work.

Can you pull the PDC up anf flip it over and open it up? It's been a awhile since I had worked on one. if so you can see the bad wire part. Unless its seal up.

I have the pdc open and i can see all the wires.

Well find the wire that goes from the fuse to pin 35 on the relay repair or replace it.

Used to fix a ton of Dakota's with a no-start....90% of the time it was a red/white wire going to the PCM which had corroded at a splice in the harness. This was a B+ battery power to the PCM. ASD's etc will NOT turn on without the PCM powering up....
The splices are usually along the left inner fender area...on a Full-size it could be along the firewall...time to start stripping the harness....

It is fixed. I feel stupid. It was the fuse. Always check the easiest first, I learned again for the hundredth time. Thank you all for the help.