August 02, 2013 @ 11:26 EDT


Last night I received an ebay-special GM ODB1/ALDL dongle in the mail. This morning I brought it over to the new mechanic (different shop, different tech, but under the same umbrella/ownership), who filled me in on the wire tracing they'd been performing. Along with a fourth computer.

In short, the wiring appears to be good, and the computer is actually grounding the ignition control reference line. No reference voltage means the distributor pickup coil can't detect the engine rotation. No rotation equals no spark and no fuel. Because.. why bother?

But back to MALFFLG3.

In the earlier days of this problem, I'd mentioned that I'd had a PROM-related problem with the old POS Lumina I'd owned for a while, and that it may be a factor in this truck's woes given that it helps drive the computer. After I finally got the data link working, that theory just gained considerable credence:

MALFFLG3, ie Malfunction Flag 3, is non-zero. According to the charts, this translates to "Error 51 - EPROM Checksum Failure". Well, well, well! The original factory PROM has been moved from computer to computer, with nobody giving it a second thought because "PROMs never go bad!"

The mechanic's going to call up GM and order a new PROM, which is specific to the VIN of the truck. Keep the fingers crossed; this is probably the underlying cause of everything. Even the distributor may not have actually gone bad, though given the rust and whatnot it needed to be swapped anyway.

Anway. In about an hour the mechanics will have had my truck for three weeks. Here's to hoping that doesn't become four.

Posted by Solomon Peachy | Permanent link & Comments | File under: Photos, Life and other BS