The
Malibu Mystery
Are you ready for more detective work on the Malibu? Get
your notepads out, reread the customer concern CAREFULLY. Then read the
manufacturer’s diagnostic process. The solution will present itself.
Notice that in step 7, they took the wrong step (8) and
replaced the ECM. The reason why they did not go to step 9 was because it told
them to clear the DTCs and see if the DTCs returned. They DID NOT. Remember,
this is intermittent and the shop could only duplicate it once.
The DTC P2101, referred them to testing both the ETC and
TAC fuses. Both fuses were good and both fuses were replaced.
Remember, also, that DTC P1682 is Ignition 1 voltage low,
and P2101 is a TAC module performance code. P1682 sets if Ignition 1 voltage
falls below 10 volts for 2 seconds. Remember, this is an intermittent
condition. If you have a low voltage code and another code, do you typically go
for low voltage first? Hmmm.
One reason why the fictitious character, Jack McGinnis, was
able to solve the mysterious car crashes in my novel, The Electronic Killer,
was because he took notes and constantly referred back to them-just like the
fictional Columbo did in the series.
Checking fuses, powers and grounds is part of the diagnostic system check vehicle along with DTC's and power modes and should have been checked early on in my opinion. I believe they replaced the ECM with a "used" PCM already. Not sure I understand what's going on here, did they get a "bad used" ECM? I see they should have checked for intermittents before replacing the ECM back in step 5 or 7 but some people do not know how to properly check or induce intermittent conditions especially as it relates to electrical issues. I agree that taking good notes is essential, I also make a copy of my wiring schematic and write down any expected voltages, resistance values or currents I expect to find during my diagnosis along with what I actually found so I can refer back to them later if needed. I also write down all or any DTCs' and then diagnosis them based on priority, GDS2 does a pretty good job of prioritizing them for you, also using the Review Stored Data portion of GDS can help by looking at all the data and hoping to see something out of the ordinary, that is if you can duplicate the concern. Kind of like a Snap Shot using Tech2. This seems like it could have been an easy one to miss-diagnosis if you were not careful. I still would have suspected a ground issue (high resistance) being the culprit or a poor electrical connection.
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