NO Bus/no start

B

Big Bertha

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Joined
Mar 14, 2013
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33
Ok guys, gotta pick your brains for a minute. Got a 1999 2nd gen 24v I'm working on for a friend with a No Bus message on the dash. We tried everything so far, cleaning connections, dielectric grease, checked the alternator connections and the alt itself, all the wiring, even the connectors behind the dash. No fix yet, but here's the kicker, if you plug a obd code reader into the obd port and leave it in, the dash works, can bus works, lift pump runs and truck runs fine. Soon as you un-plug the code reader, no bus message, lift pump shuts off, dash doesn't work at all, tried pinning out the obd port and still nothing. Any ideas or help would be appreciated.

Thanks,
Big Bertha.
 
sound like our E350 at work .. runs till you plug it in ... then no start ...LOL .. damn ford anyways .......LMAO !!!!!

I would guess that you ecm is indeed searching for a ground and is not finding one till you plug in your programmer and it finds a small source ground and lights up ...... grounds and the plug @ECM .. body control modgule maybe ???? seen all types do fun stuff to nice trucks ........
 
Ive looked at all the grounds I can find, Ive taken them all off, wire wheeled and brushed them, the only one I was unable to find was the one that's on the back of the engine supposedly and check it. This is just starting to bother me I mean I told the customer that if he wanted to he could just go to autozone and buy a cheap $40 code reader and leave it plugged in(jokingly) and sell the truck(flip truck) I mean its a cheap security/anti theft devise but like a typical technician I still want to fix it correctly.
 
Maybe I'm thinking 1 dimensionally, but if it's searching for a ground, is it not likely that an ECM/BCM could probably be faulty?

If you have any to try that would seem to be the next way to go.

Mark.
 
Curious to see what fixes it. My truck does the same. Doesnt really hurt anything but is annoying. Is there an internal connection to ground in the ECM that could have broken loose? Bad solder? A pinout of the ECM would help as well.
 
try grounding the ECM to the body with a seperate wire ....

Might also do some continuity testing on the wiring between OBD2 port and the ecm ........ theres bound to be a short somewhere alsong these lines I would suspect.......
 
Any thing that happens odd ball I always load test powers and grounds to the ecm and related components and ign with a old glass head lite , but don't ever back prob or stick any thing other then the proper test pins in the terminals !!!! Paper clips and pins are not what's made for the pins, and with the write pin you can check terminal tension. This is a back to the basic test - some times you just need to firget about what you have done and start over. And also if all is good and data link tests good you may want to start unplugging other things on it like abs and such to see if any Chang Happens
 
I agree Emcc86 .... always use the correct plug to do testing .... nothing more annoying than trying to go behind someone and figure out what they screwed up worse than it already was ...lol
 
I find many intermittent drivability problems daily from prier repairs that techs did damage well testing
 
I just love to find scotch locks ...AAAAHHHHH !!!!!! DAMN IT .... get a soldering iron and stop being a lazy ass..... .....LOL ... off my soap box now .
 
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