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Old 11-02-2019, 07:41 AM   #10
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Join Date: Jul 2014
Location: North-central Virginia
Posts: 475
Re: Dakota Dig. BIM-01-2 info for Gen IV

To edit my post above: I was browsing some alldata stuff, and realized the ecm does know what gear is selected.

PRNDL Display

The IPC displays the selected gear position as determined by the ECM. The IPC receives a serial data message from the ECM indicating the gear position. The PRNDL display blanks if:

The ECM detects a malfunction in the transmission range switch circuit.
The IPC detects a loss of serial data communications with the ECM.
Evidently, the prndl position is bounced through a lot of modules before being displayed.

Transmission Control Module --> Engine Control Module --> Body Control Module. Here, it switches to low speed data, and goes to the Instrument Panel Cluster.
1987 V20 truck, with a 2010 LMG 5.3, and a sm465 tranny.
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