LS1 PCM and Cruise Control Installation in 1933 Willys
10-14-2012, 05:00 AM
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LS1 PCM and Cruise Control Installation in 1933 ****** Yesterday we installed cruise control on a 1933 ****** that has an EFI Connection 24x SBC with LS1 PCM. While everything went together well, the cruise control has a few "bugs" that we would like to iron out.
Cruise control will not set until 45 mph
GM's cruise control should set at 25 mph. We cannot set cruise until 45 mph. When set between 25 mph and 45 mph, the system engages and then quickly disengages. Cruise control will not remain ON until it is set at 45 mph or more. We are speculating something to do with the 4,000 PPM VSS signal, but the scan tool shows MPH incrementing smoothly with the speedometer.
Surging off highway
When using cruise control at lower speeds (about 45 mph) and off highway, there is often a feel of surging. When on the highway, 60 mph or so, cruise control works great. The variation in speed is only about 3-5 mph for a 5 mile span. This is a 2500 lb vehicle with a 380 hp engine. Our thoughts are...
- the location of cruise cable at the throttle body linkage (fulcrum location from shaft center)
- light vehicle with powerful engine (hmmm? unlikely)
Any ideas?
Here are a few pics of the install.
Temporary linkage adapter...until we make a new one.
Early cruise switch allowing only Set/Coast operation.
Brake switch from 1995-1998 F-Body.
VSS signal from LS1 PCM secondary VSS output.
1998 LS1 F-Body cruise control module located under driver on bottom of vehicle.
Secondary VSS output set to 4,000 pulses per mile.
Cruise control will not set until 45 mph
GM's cruise control should set at 25 mph. We cannot set cruise until 45 mph. When set between 25 mph and 45 mph, the system engages and then quickly disengages. Cruise control will not remain ON until it is set at 45 mph or more. We are speculating something to do with the 4,000 PPM VSS signal, but the scan tool shows MPH incrementing smoothly with the speedometer.
Surging off highway
When using cruise control at lower speeds (about 45 mph) and off highway, there is often a feel of surging. When on the highway, 60 mph or so, cruise control works great. The variation in speed is only about 3-5 mph for a 5 mile span. This is a 2500 lb vehicle with a 380 hp engine. Our thoughts are...
- the location of cruise cable at the throttle body linkage (fulcrum location from shaft center)
- light vehicle with powerful engine (hmmm? unlikely)
Any ideas?
Here are a few pics of the install.
Temporary linkage adapter...until we make a new one.
Early cruise switch allowing only Set/Coast operation.
Brake switch from 1995-1998 F-Body.
VSS signal from LS1 PCM secondary VSS output.
1998 LS1 F-Body cruise control module located under driver on bottom of vehicle.
Secondary VSS output set to 4,000 pulses per mile.
Last edited by S10Wildside; 10-14-2012 at 05:19 AM.
10-14-2012, 05:11 AM
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While this is not really a how-to thread, it contains photos of pretty much all you need to see related to the installation of a 1996-newer GM truck or F-Body cruise control module. This will work with any application that has an available 4,000 pulse per mile VSS output (even as early as the 1990 TPI ECM). Here's a schematic.
