1993 Blazer. Speedo off, no odometer, no cruise...

[MrFleming007]

OK, with the help from the wiring diagram and another forum, I tested all the wiring for the cruise control yesterday. Biggest difference I noticed from the wiring diagram is that we have no white wire going to pin G on the cruise servo. It looks like this wire was never present on the 92-94 models? All other wires give the correct voltage ratings at the correct times with the exception of the vss signal wire.

This wire starts off at .04 volts at idle and increases to a max of 2.79 volts at about 20 mph. Never gets any higher than this as speed increases. Out of curiousity, we stopped at the junk yard and picked up a couple additional VSSR/DRAC modules. After setting them all to the correct tire/ Axle ratio we tried swapping them in and taking it for a test drive. First replacement module gave the same vss wire readings as the original. The 2nd module started off at 5.05 volts at idle, then dropped to .07 volts as the vehicle started rolling. This one too, maxxed out at 2.79 volts at around 20 mph and never got any higher.

So..... where to go from here?

 

[MrFleming007]

Allright, here is where I'm at. I've tested all wires according to the diagrams and everything looks good, but still no cruise. Tried three different cruise modules, still no go. Replaced the DRAC module with another (programmed to to correct gears/ tire size) still no go. So I'm at a loss. Here are the wires that I'm dealing with and the voltages that I'm showing on them.

Cruise Module Connnector

Pin A- Gray Wire (Cruise on/Off); Shows 12v when IGN on and cruise switch is placed in "on" position, 0v when "Off"
Pin B- Dark Blue (S/C Signal); Shows 12v as long as button at end of cruise lever is pressed, 0v otherwise
Pin C- Dark Green (R/A Signal); Shows 12v as long as lever on cruise stalk is pushed to far right position, 0v otherwise
Pin D- Brown (Cruise Release); Shows 12v when brake pedal is pushed, 0v otherwise
Pin E- Black w/ White stripe (Ground); Has good ground connection. Connects to Chassis Ground through orange three way connector on Convienence Center.
Pin F- Pink w/ Black stripe (IGN); Shows 12v when IGN is "on". Connects to 20a "Gauge" Fuse through Orange three way connector on Convienence Center.
Pin G- N/A, no wire
Pin H- N/A, no wire
Pin I- N/A, no wire
Pin J- White (PCM input); Shows 11.47v when IGN is on. Connects to PCM at connector C1/B10. Not sure what this wire actually does.
Pin K- Red w/ White Stripe. (VSS); Voltage varies with speed, starting at near 0v at idle, increases with speed. Has never shown above 4v. Connects to DRAV/VSSB module through Orange three way connector on Convienence Center, then to Pin 4 on DRAC/VSSB Module.

The cruise stalk in new and appears to be functioning properly. Have checked and cleaned all connectors between it, the PCM and cruise module and all are getting good continuity. The VSS is new and appears to be functioning correct. I can only at this point assume that the DRAC/VSSB module is functioning correctly as the RWAL system is working, and the speedometer is working and showing within .5 mph of GPS speed. The voltage on the Speedometer wire and RWAL wire is the same as the voltage showing on the vss cruise wire. The only wire whos purpose I am not sure about is the White PCM wire...

The Cruise modules I have tried are as follows;

P/N 25140076. Module that came in truck.
P/N 25140906. Came from 1994 K1500 Blazer with working cruise control.
P/N 25074973. Came from 1989 K2500 Silverado with 5.7l and working cruise control. This Truck did not have the White PCM wire.


So, at this point, I'm looking for any ideas. Thanks in Advance everyone!

 

[MrFleming007]

Well to update this, on Friday we got a CEL. Checked the code and it was for the egr. Pulled the egr and it was full of carbon and not holding a vacuum. Figured while we were in there replacing the egr, we would rebuild the TBI and replace the PCV valve. Truck runs even better than before now and.... CRUISE WORKS! Not complaining about that, but whats the relation here? Could the pending egr code have prevented the cruise from engaging?

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[SunlitComet]

what was specific code?

 

[MrFleming007]

Code 32- egr failure

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[SunlitComet]

there is no relation to the cruise, not even power wire wise so that will remain a mystery for now. You had gotten the 32 code becuase your short term fuel trim fell outside a calirated window when the egr vacuum solenoid closed off vacuum supply to the egr valve itself which can be caused by clogged passages. My best guess at this time is that you may have disturb a ground wire when doing the egr work that may have had a dirty connection.