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Home >> Buick >> 1990 >> Reatta 2D Convertible, 4T60/ME9 >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes - BCM >> BCM Trouble Code Charts >> Code B420: Courtesy - Twilight Light Relay Circuits >> Note on Intermittents

Note on Intermittents

Since all 4 (or 3 in the case of Reatta) groups of relays can cause an intermittent condition, see NOTE ON INTERMITTENTS (in each CODE B420 Cont.) for each of the relays.

Fig 1: Code B420: Circuit Diagram
G90D21777
Fig 2: Code B420: Flow Chart Twilight Light Relay Circuit
G90B14622
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