No MPH on SM or Powerlogger, but no code 24?

[696]

I have a Autometer electronic speedometer installed and I'm using the Casper dead end with a VSS converter. I tapped my signal into the brown ECM wire in the stock VSS assembly to send it to the ECM. I went out for a test drive and have do not have a code 24 but the scanmaster and Powerlogger show 0 mph? When I had the stock dash in it worked fine. The only error I made was during a prior hook up I but the output signal from the VSS converter to the 12 volt positive feed from the stock VSS instead of the brown ECM wire. Could that have damaged something?

 

[TurboBob]

possibly.

Many chips have code 24 turned off, since its easy to cause that code with braketorquing.

Bob

 

[696]

It's a TT chip and the code 24 is active because I've tripped it before within a 1/2 mile of my house. Last night I drove a good 7 to 10 miles with no code. I plan on running the SM back to the ALDL and see if I can get a signal there. Do I need to replace the 2.2 chip to the 2.1 chip or does it make a difference?

 

[Eric Stage I]

Another thing that can prevent code 24 is if the park/neutral switch shows that its in park all the time.

 

[696]

All stock shifter and cable, with 200R4 tranny. How can i check to see if this is the problem?
oh the speedometer is approx 5 to 6 off at the read out, autometer can be calibrated, could that have any effect on this?

 

[Eric Stage I]

The speedo reading is not important, only the reading the ECM see's (on powerlogger).
Here is the park/neut indicator:

 

[696]

Thanks Eric, I'll check the park/neut box. If it is showing going into 3rd and 4th gear am I good? That means the ECM is picking up speed signal correct? Is there anything I should look at on the timing gauge? Or any other gauge that will be off if the ECM is not getting a speed signal?
Thanks for the help.

 

[Slow91z]

Nope the 3rdgear and 4th gear switches are in the trans so they can work even without a speed signal.

 

[696]

PL shows that park and neut is working fine, I plan on checking the output of the VSS converter tomorrow and making sure that there is an output where it connects to the "brown" wire to the ECM (i believe it should be 5 volts). After that hooking up the SM to the ALDL and see if THAT shows a MPH. I'll report back then, see if there are anymore ideas

 

[TurboBob]

if there is no MPH showing on the PL, then rewiring the scanmaster won't help, as both setups read the data from the same spot in the ECM.

Look further into the wiring or the interface unit.

Bob

 

[696]

Clear and thanks, I'll check the VSS output. I know the signal is coming up from the tranny because the speedometer is working. I know the brown wire is good because I sent a signal thru it and the A10 harness end and it was good. It's looking like the VSS converter.

 

[696]

With the car running approx 9.4 volts coming off the VSS converter to the brown ECM wire. The wire was not connected to the ECM, just the signal wire. When I tested the brown wire it showed 12.4 coming off the ECM by itself with the car running. I don't believe I damaged anything because the hotwire to the stock green VSS box and now i found out the brown ECM wire BOTH have 12 volts coming out of them. I have a signal from the VSS converter to the ECM I can't figure out why the PL is not reading it?

 

[696]

Just got off the phone with John from Caspers. Bad VSS converter, bench test showed it was bad. Caspers is sending out a new one tomorrow and I'll post back when it's in. Can't see why it wouldn't work now but we'll see

 

[696]

New VSS converter is in. MPH is back on the Scanmaster and Powerlogger. Can say enough about the great customer service from Caspers