Electrical Gremlins

[moburchette]

Hi Gents, I got a good one for you here. 2005 CTD was having a lot of the symptoms described in the "no bus" discussions. Except the "no bus" part, my instrument cluster was totally lighting up while driving, all the warning lights as well as all gauges blinking to zero (no "no bus" code or any other problem code). At first didn't affect drivability at all, then a couple times the motor coughed, then today, coming home after a long week on the job she gave up the ghost, dead in the driveway. Turn the key, I get radio, headlights, no more, anything associated with or controlled via the instrument cluster or multifunction switches, nothing. In fact the only light that does work on the instrument cluster is the door ajar light. I've checked all fuses, fusable links, and grounds, all looks well.

3 things have been done recently

1)fuel filter change (read in other posts about diesel fuel into elec. connections, have already checked and cleaned with no result)

2)radiator flush including thermostat change.

3)about a half tank of B100 biodiesel was mixed in with reg. ULSD.



I have until the end of the holiday weekend then will be forced to tow to the big D, please help.



Part 2: woke up this AM and just for gigs tried to start the truck, same at first then i noticed the PRD21 switch was lit up, jiggled the key a bit and boom, cluster lit up per usual, truck started and idled fine, repeated several times with same result. now ABS light is on????

 

[sag2]

Was the PRND2L "boxed out"? If yes, the bus was down. It can be a module on the bus taking it down or a bus wire shorted to power or ground. Next time it acts up, start pulling fuses one at a time to see if you can kill the offending module or circuit.

Find the easiest module to access and measure the voltage on the bus wire while it is acting up. The ABS module might be easiest, and you are looking for the white wire with a violet tracer.

 

[moburchette]

Thanks for the Reply, thing is really going haywire now, no longer drivable. will pull fuses to next time to pinpoint module. not sure what you mean by "boxed out" though?
cheers

 

[moburchette]

looks like i found the culprit, main lead from batt to alternator, rubbed through insulation and shorting to frame...

 

[moburchette]

wrong! didn't fix it. AGH...

 

[sag2]

Did each of the letters of the display have a box around them?

 

[moburchette]

No, just normal display. guys at the local garage bypassed the elec. ignition switch and problem seemed to disappear, replacing switch today with fingers crossed.