Crank sensor testing? - Page 2 - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat
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1987-1991 Parley with regards to your 1987 to 1991 Bonneville, Olds 88 or Buick Le Sabre Please use General Chat for non-mechanical issues, and Performance and Brainstorming for improvements.

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Old 09-29-2007, 02:55 AM   #11
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I should have posted the fix before. Thanks for the reminder.

My issue was actually a bad physical ground between the ICM and it'* mounting bracket. There was too much corrosion between the two. As a result, the Crank Sensor wasn't being given a good "sensor ground", and it couldn't function properly and return a signal to the ICM. The voltage between the "sensor power" and "sensor ground" was very low... far below the 10v that the Haynes manual says it gets.

Cleaning up the bottom of the ICM and the top of it'* mounting plate restored good contact, and it fired right up.

Funny thing though: I tried another ICM and set of coils on it, to see if it those were the problem, and those didn't work either. It took some actual sanding to restore good contact.
I'm Jon. I'm completely stock, no mods.
1993 Bonneville SSE 191,000 miles "The Work Beater" Imperfect but quite tolerable. Stock.
1996 Buick LeSabre Limited, 181,000 miles "The family car" Custom CAI, F41 Sways.
Sold/dead, but not forgotten: 1989 Bonneville LE "Bonnie, the Sport Utility Car" STB from '92-'99 Bonnie, Delco (Type II) Ignition system
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