I bought a burnt chip about two weeks ago and replaced the burnt chip that was in there that had the VSS disabled. I wanted the VSS Highway mode so I bought a new chip. Anyways after putting the chip in and rewiring the VDO programmable speedometer and a 16K Hall Effect speed sensor with a SGI Dakota Digital signal convertor. I am now getting a VSS code error every now and then. It only happens every so often. It triggered the code last night after driving about 20 miles on a drive hitting highway speeds I was going home and at about 20mph the ALDL light came on and in about a minute it went off. I had my programmable scan tool and checked the code within that minute. I am not sure why it is triggering intermittently like it is!!! All the equipment is new speed sensor, chip, ECM, ect… I even cleaned and reset the IAC sensor and ports and reset the ECU just prior to the drive thinking it was that. And disconnected the spark advance wire to the HEI and set the RPM to 500.
When I got home it was idling around 1400RPM, a little high… Not sure why? When I left after resetting everything and adjusting the RPM it was purring at 900RPM at rest.
Could it be a bad TPS or MAP? NEED ANY ADVICE!!!!!

 

double check all the connections for the vss and converter. The code 24 could be caused bye a faulty ecm.

 

I just rewired the convertor box and have a painless wiring kit that tags out the two specfic wires fo the VSS high and VSS low. and I used the sensor ground on the dakota digital for the low and supplied the ECU with a 4000PPM for the high.
I am thinking that it may be a bad ECM. I know when i was resetting the IAC and had it unhooked I let the engine warm up to 180 degrees for about 5-10 min run time. I did notice it did not throw a code for the IAC code when it was warming up and disconnected. It should have right?

 

There are no error codes for the iac.

 

http://chevythunder.com/vss_code_24_sd_199092.htm

 

Make sure all you wires are away from your ignition wiring to prevent emi.

 

Good call! i will check that out.

 

any progress? Who programed a memcal with no vss ? I didn't think it was possible to take it out of code the $8d has the option of magnetic or optical input.

 

I had my old chip programmed like 8 years ago with the VSS programmed out supposedly… But I was unsure, so I bought a new chip Utilityguy2 from this website with the VSS enabled. So the progress… I did check the ignition wire and stripped my harness apart over the weekend and loomed and ran the ignition wire separate from all the other wires. I took my new MSD 8.5mm plug wires off and re ran them away from all other wires. Then took it for a drive, I drove it up to highway speed and low speed in town for about 30-40 miles turning it off here and there, no check engine light!!! Then about three blocks from my drive way going 20 mph, it comes on!!!!!!!! GRRRRRR, I let of the throttle and the light goes off. Like it help the code error for a split second, but not long enough to hard set the code. I checked all the connections to the Hall Effect Speed sensor too. The engine runs great, little rich smell of fuel, but the tail pipe is clean.

I just don’t know anymore what to do… Should I replace the ECU? One thing that I did check was my TPS sensor. With key on ignition the voltage was .54V on the nose and I slowly opened the throttle and it climbed evenly, but only to 3.9V max. I thought it was suppose to go to closer to 5 volts?