[time-nuts] GPS receiver in GM 2001 OnStar?? Found the location

randy warner randy at geodetics.com
Fri May 16 18:32:30 EDT 2008


The OnStar did in fact use the old VP/GT boards. They are functionally and
electrically identical. What MIGHT cause a problem is that these units might
have a different software load. The original "GT" receivers did not have
NMEA capability. I don't know if these old Onstar units ran binary only.

If there is a P/N sticker on the receiver, I can tell you what the receiver
is capable of, unless the receiver has some sort of internal P/N.

1.	If the P/N starts with "R1", the receiver speaks binary only. The
R1xxxNxxxx series are "GT" receivers. 

2.	If the P/N starts with "R3", (R3xxxGxxxx for instance) the receivers
are "GT+" and should speak both binary and NMEA. 

3.	A secondary way to tell if your board speaks NMEA is to look at the
software revision. If the revision is below "2.2" the board is binary only.

As I've mentioned before, the easiest way to figure out what you have is to
download Rick Hambly's TAC32 program at: www.cnssys.com. TAC32 will figure
out how to talk to just about any Motorola receiver ever made without
operator intervention. It cycles through all of the various communications
protocols automatically and tells you what the receiver is.

Randy Warner

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Richard Hall
Sent: Friday, May 16, 2008 2:39 PM
To: time-nuts at febo.com
Subject: [time-nuts] GPS receiver in GM 2001 OnStar?? Found the location

In my 2001 Buick Park Avenue the GPS and Analog cell phone are in the trunk
behind the passenger side seat.

I removed the unit and the GPS board looks like a Motorola Oncore VP/UT+/GT
and there also was an antenna that looks like a, "Motorola Antenna 97 GPS
antenna", Motorola part number is GCNAC1232A.

With GM's analog OnStar no longer supported, this may be a low cost auto
salvage item.

Can some one confirm that GM used a board with the same pin outs of the
  Motorola Oncore VP/UT+/GT. With no previous GPS board experience, I do not
want to damage this board by being wrong on the power connections.


Richard Hall

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