Expert: Ernest (Ernie) Kenward - 5/11/2008

Question
QUESTION: I am not sure if it is related, but during this past winter we noticed a lot of static in our truck. So I attached a ground strap that would touch the pavement about 6 weeks ago.
On Saturday evening I turned the signal light on and it made one blink. On Monday morning I went for a ride then I checked the fuses under the dash, all were ok. So I lifted the fuse cover under the hood, the hazard fuse was blown, so I went to start the truck to go get a new one. It would crank over but not start and when the key was on the ASD fuse would just click. I replaced the hazard fuse. All signal lights, heater motor etc... work it just wont fire up.
I got it towed to Canadian Tire and they hooked it up on their scanner and nothing shows up.
The mechanic showed me after he cranked it over for a few seconds and left the key in the on position, the odometer would say NO BUS. He claims he has no idea where to look or how to fix the problem. Can you give me some advice???

ANSWER: My first order of business would be to check the electrical diagrams so as to identify whichever circuits were not working so that I could then trace them through.  I have that sort of information for my rigs but not for yours, so I cannot be very specific in any help I can give you.  

My instinct is that the static strap is not an issue, and cold dry weather static really only is a problem with electronics if one is working on an open circuit board on a bench, and not when the circuit is wired into its application, with all the overvoltage transient protective devices in place that one would normally find in an automotive environment.  More to the point, a static discharge causes immediate damage (shorting a semiconductor junction, effectively making a diode into a "biode") at the instant it happens the vast majority of the time, and rarely has a latent effect.

In your case, the problem may well be a bit of corrosion here and there which has simply caused connectors to oxidise and go open.  Often, unplugging connectors (and fuses, for that matter) and then reseating them clears that problem.  You might try that and, if it does cause circuits to begin to work, I would then reseparate the connectors so as to clean and then grease them, using any one of a number of products used for servicing electrical hardware such as relays and contactors.

You can probably just consider the "NO BUS" message as simply a word from the gods of technology that there is hope of a simple solution and that you need not consider switching to public transit just yet!

Follow-up:

Rereading your original memo clarified a point about the NO BUS message: you note that this was seen just after a mechanic had cranked the engine, but without it starting.

I would call that message a NON-issue in this case.  It would appear to be the message that is shown whenever the system voltage is below some predetermined value that is considered a "good" main bus voltage, say 12.0V or so, indicating battery only on the system, at about 70 to 80 percent charge.  Usually you would not see this message because the alternator, on engine start, would bring the system up to 14 volts or more to give the battery its initial bulk charge.

In any case where the engine does NOT start after cranking, the battery voltage would remain low, making it possible to see this message.  Under cranking, the battery voltage will drop to ten volts or less, and this would very likely generate the NO BUS message if the cranking is prolonged or does not result in a successful start.

The problem you probably do have would come back to a high resistance connection in the battery/bus/starting contactor/starter motor circuit; and a common source of this problem is a battery clamp that has started to become loose or corroded.  Simply tightening any mechanically loose connecttion may be all it would take to clear that problem, although I do recommend that cleaning, greasing (using electric terminal products) and retightening all bolted or clamped terminations in that circuit would buy you back reliability once again.

A possible second problem may just be an old and tired battery.

I do think that this should be a problem with an easy solution, and it would be kind of "emPOWERing" for you as well to dig into it a little yourself.  A Haynes guide to your vehicle might  be helpful, although many of them are not as complete as the OEM shop manual; still they provide guidance to the newcomer.

Good luck again ... EGK

---------- FOLLOW-UP ----------

QUESTION: Well, first of all I would like to thank you for all your help.
Prior to me getting your follow-up response, Canadian Tire called saying they had the truck running. When I picked it up the mechanic said it was the 20amp Engine Control 2 fuse that had to be changed and it was ok now.
I drove the truch home about 5 blocks parked it and about 5 minutes later I started it up drove out to the end of my driveway and it shut down again. So I had it towed back up to Canadian Tire again. Then I read your follow-up response
When I went to pick it up at 4pm he showed me that he had put a jumper wire from a blue/green wire that goes into the computer on the firewall and aligator clipped it to the engine. The truck will start and when I take the wire off the engine will shut down.
Now when it is running the check engine light is on and the engine sounds like it is running on 5 cylinders.
The mechanic tells me that he THINKS that I need a new computer.
I took your advice and installed a new battery and new battery cable ends and it is still doing the same thing.
I am definately going to be looking into those manuals as the shop rate is very expensive.
Would a diagnostic test at a Dodge Shop tell me what the problem is?
Again Thank you for your time.
Dennis

ANSWER: Not having the manuals or any other specific details on the Dodge Ram 4x4 (for the simple reason that I do not myself have one of these vehicles - but I do have a full complement of documentation on the vehicles I DO own, and I highly recommend that practice), I cannot advise you as to the specifics of the CT mechanic's clipping jumper wires to or around the ECU.  (Incidently, I did not advise you to buy a new battery and cables, but suggested that you check them out for problems, and further suggested a process whereby you could recondition the connections.)

What I would advise now from the distant chair in which I sit is that the time has come for you to get the vehicle into the hands of a shop that can do appropriate systematic tests in order to properly isolate and identify the problem.  At this point, the shop at a reputable dealer would probably be your best bet.

What you want at this point is to get the best value for the repair dollar, and that best value will come from a proper diagnostic procedure.

Good luck ... EGK

---------- FOLLOW-UP ----------

QUESTION: Ernie
I totally agree, I installed the new battery at my own free will, as the other one was getting very old. After checking over the connections I noticed that one of the injector wires was off, once I installed it properly the engine started running properly when I have the jumper wire on, as soon as I take it off the truck shuts down.
I have an appointment at Rainbow Chrysler the local Chrysler Shop on Tuesday morning at 8:30am. Hopefully they can find the problem. Your assistance has been great, as it has at least got my mind thinking like a backyard mechanic again, as I have not worked on vehicles in over 10 years since I had my back operated on twice.
Again Thank you.
If you have any intyerest in snowmobiling in Ontario, please check out our website. www.rcsasnow.com
Dennis

Answer
Would you believe that we here in "Lotus land" had snow as little as three weeks ago, some 34 cm in Nanaimo just over on the island, which wreaked havoc with our daughter's tournament volleyball game that Saturday.  They still made it to Ottawa last weekend.

We have been on the wrong side of the jet stream until only the past week ... and it may be too soon to relax just yet!

I shall check the site.  Lots of good snowmobiling in the BC interior too, and in the Peace River country in which I once lived.

Good luck with the check-out.  Let me know what transpires.

Cheers ... Ernie Kenward