Otay, here's the challenge.

I have a 99 Dodge Ram 1500, 5.9L, 2wd, a/c, auto tranny. I've read many threads about shoot it, burn it, trash it, etc, but it's my daughters and she turly loves it so I've gotta fix it.

History: Just one year ago, I rebuilt the tranny, new cat, distro cap, button, plugs, plug wires, crank sensor, O2 sensor (pre cat) and had PCM reprogrammed for all new work. Ran great up to a couple months ago.

A couple months ago it started to throw a P505 (idle air control system issue) and on occasion a NO BUSS on the odometer. I replaced the IAC valve. Ran great for a couple days and went back to same code. I'm in Colorado and it has been unusually hot (breaking records for days now since it's been in the 100's.) I tried 3 more IAC valves (all except the last one from Auto Zone; last from Advanced Auto) and code kept coming up. Replaced pre cat O2 sensor and got a couple more day of code free issues. A couple more days of problem free driving and P505 came back. Pulled gauge console, check all wiring/connections behind, under and around stiring wheel shaft, next to emergency break pedal, thru fire wall. All good. At night wiggled every wire I could get my hands on and no spark noted.

Today, temp at 101, it took me 3 1/2 hrs to go 40 miles. Left for work early morning where the air temp was around 80. Left work, air temp at 100 and heading down the highway a complete shutdown and NO BUS on odometer. It shut down 10 more times in that 40 mile trip.

The shutdown would be without any fanfare or warning. First there was some hesitation as if the tranny was shifting to lower gear, speedometer drops to 0, tack followed a couple seconds later and all gauges pegged to 0. Radio, lights, blinkers, all worked fine. Dummy lights lite up with key on.

Each time the shut down occured, I'd unplug the 3 connectors on the PCM, unhook the main terminal on fuse box in engine compartment with the key on. Generally nothing happened but what I did notice was as I plugged the 3 connectors back into the computer, nothing happened with the first and second connector being plugged back in. When I plugged in the 3rd (closest to engine with key on and radio on an AM station) I would hear lots of static and the ASD relay buzzin to beat the band. When I'd plug in the 3rd connector all the way, the static and buzzin went away and the engine would fire up.

It could take anywhere from 30 seconds to 1 hour to get the ASD to buzz for the engine to start. It would always crank after shutdown, but not fire. So there was no pattern as to time waiting for things to "cool" down or specific pattern to follow to get a buzzing relay. I could plug in the main treminal on fuse box, connector 1, 2, 3 or 3, 2,1, or 2,1,3 etc. It would only fire when I got static from touching connector 3 to computer, plug in to stop static/ASD buzzing and off I'd go for no telling how long.

When I'd get the static/buzzing from the distro box, I pulled the ASD relay and put everyone of the 8 (I think) relays in that port and all would buzz except one. So I put that in the Horn relay slot and not sure it that relay is my problem or not.

So my fellow shade tree mechanics, any idea of what I'm facing? I have an Acutronic scanner that gives me the code and lots of other info, but not sure if it will tell me what is going on.

Any help/suggestions (other than shooting, setting or fire, or donating) would be greatly appreciated.

Thanking all responses in advance.

SCUBA Sam

 

Ok, plug in your scanner while the truck is behaving. Look and see if there is a data tidbit available for crank, and cam sensors. You are losing one or the other, and that will trip the ASD relay, and give you a no bus error. When your no start condition occurs again.... (as you know it will) see if the PCM is seeing cam and crank signal. (I bet one or the other will be missing.)

Could also be a bad ground from the PCM, or, even the negative battery cable on the battery.

Don't plug/unplug the PCM when the ignition is on..... nice way to potentially smoke the PCM. (if you let the magic smoke out, it stops working....)

I am thinkin' cam or crank sensor doesn't like the hot. I don't think this is related to your 505 code though. Unless the bad sensor is confusing the PCM... (which is indeed possible.)

 

BIL had similar issues on his Grand Cherokee. One of the things I did (don't know what actually fixed it) was to sicsonnect batter, remove PCM. Clean mounting area on firewall. Clean PCM, including contacts (electronic cleaner) and clean all connectors - all the pins. Bolted it back in, wrapped the cables leading to it in a shielding mesh, reconnected battery, and woolah! Magic. No problems. And it has been around 104 to 107 around here lately. No problems.

On his GC I detected electromagnetic interferance (O scope) on some inputs (hence the shileding) and suspected failing ground. I also installed a ground wire from firewall to pPCM mounting screw.

 

First, what Heyyou said.

then, +1 on the electronic cleaner on all ecm contacts, remove and spray the large white plug in the distibution block too, it's very common for it to be loose and cause the no bus issue.
Sand the paint off the firewall where the ecm ground connects and on the ecm itself.

 

HeyYou has helped me with both of those problems you've been having just in the last week!

That p0505 was persistant and I finally dealt with it by putting in the iacv I replaced with the battery disconnected and somehow it was able to relearn its setting and all was good in the neighborhood.

Then it started dying. Was the all black pcm connector on the right. I cleaned and slathered it in dielectric grease. I think the plug is just worn because it has died a couple times since cleaning it. I think its the harness side that's getting worn.

And I had no bus. I pulled the big white connector for the distribution box and slathered that in dielectric grease as well and it has worked.

I don't know my solutions will help but I hope they do! good luck!

 

To all,

Thanks so much for the tips. I started at the crank sensor and found both bolts had significantly loosened up. I replaced it a year ago and it's taken that many bumps to loosen it up. So after some serious coating with thread lock, she fired right up and no issues so far. I had noticed that after hitting a bump it did go thru the shut down problem while I was driving and forgot about that until I checked the mounting bolts. WOW what a pain for just two loose bolts. I will go thru the other recommendations after a day or too to make sure this was in fact my problem. I want to make sure this was the problem and I can't imagine it wouldn't be with it as loose as it was.

Still getting the P505 code and will try disconnecting my - cable on battery and install the IAC. My idle is at 800 and no dieing or stalling under load with the Check Engine lite on. My scanner does not read cam or crank sensors. O2 sensors (1 and 2) fluctuate from single to tripple digits and back. So I'm reading those as functioning. Thought of replacing Throttle Position Sensor but want to make sure the NO BUSS is fixed and move on from there.

Again, thanks for the tips and saved me a bunch of time and $$$$$$. I've always told my kids that "experience is what you get when you are looking for something else". So now I've a bunch of experience on a NO BUSS!

Sam
(When you're too cheap to pay someone to do it for you, ya gotta do it yourself!)