liquidh8

Ok help me out here guys PLEASE!. Hop this is in the right place.

I Just converted my wagon to the autometer in dash electric speedo. (all other gauges too) I bought the VSS for the speedo. The speedo is reprogramable, but the VSS isn't The speedo has a signal out pin that the manual says you can run to the PCM, but this isn't a PCM and by searching I read somewhere that the TBI uses 2 pulses per minute, or mile? Is there a way to take to original buffer box from the factory speedo and make it work with the EBL.

When I have the signal out wire from the speedo to the ECM, when I am doing like 25 MPH, the WUD says I am doing like 175 and the speed limiter shuts the car down. So I unhooked the VSS, but I have a high stall converter and enjoy the lock-up function.

Help me out here guys.

Thank you.

RBob

iTrader: (1)

The EBL ECM is 2000 pulse per mile (2K ppm) (same as the '7747, '8746, '7165, '7749, etc.). Sounds like the autometer output is 8K ppm. First see if the autometer setup has a 2K output, if so can use that.

If they don't call 'em up and yell at them. Well, not really, but you would think that they would create something that would work with standard OEM GM stuff.

So the next step would be to find out what their VSS output is: mag, or square wave; 2K, 4K, 8K, 16K, etc, and work from there.

RBob.

liquidh8

crap. I think is is 16x square wave.
BUt I had an idea, I was gonna use a 2 piece speedo cable, put the autometer vss in the brak for the speedo head, and I have an old factory speedo I stripped the face and alll the other crap off of, and I am gonna build a little box and use it for the ecm. Right now I am running without a vss to the ecm.

How much is this screwing me up, since the ecm thinks I am at idle all the time?

Thanks
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then maybe use the old speedo as a VSS, and hide it, and tap off the signal wire after it is buffered and send it to the speedo. I could try that.

RBob

iTrader: (1)

Without a VSS lose the TCC, DFCO, IAC throttle follower, speed limiter, lean cruise, launch mode, BLM cell used, and the idle is funny. I may have missed some. Whenever the TPS% is 0 then the ECM will think it is in idle.

Easiest thing to do is to use some 74HC74's and divide the VSS down. Only need a small open collector output to the ECM (2N3904 works). There are also some other divider chips in CMOS and HC that can be used.

RBob.

{edit: use the 74LS393 or 74HC393 binary counter. Two 4-bit counters in the 14-pin package. Can divide from by 2 through by 256 in binary increments (2, 4, 8, 16, 32, ...). So one of those will match up to the Autometer output. For +5 volts can use a 1N4001 for reverse protection, a resistor and zener diode, a small capacitor for filtering. Run the output of the divider to a 10K resistor to the base of the 2N3904, emitter to ground and collector to the EBL ECM VSS input. Done. If the speed is off by double or half then need the next divider output up or down.}

liquidh8

another quick question. There are 3 wires coming off of the factory speedo, green, black and red. They go to a box, the plug into the wire harness that also has 3 wires, a 12vdc, gnd, and the vss to the ecm. Is this box a buffer box? Does anyone know whick wire coming off of the speedo is the RAW output before the buffer box, if it is the buffer box?


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ooo, sorry, didn't catch that last post before my previous post. Thanx for the info, problem is, I am not up to speed enough to make that circuit on my own. I can physically build it, but the electrical layout would be sketchy. (been out of "electronics" for some years now).

Thanks

liquidh8

Ok, so I went to the Autometer website. The Electric speedo requires 500-20000ish pulses per kilometer. The EBL needs the 2000 pulses per mile.

SO what I did was strip a stock speedo down to nothing but the reluctor wheel and the pickup. I made a box, hooked up the speedo cable, and tapped off the signal wire to feed the guage. Recalibrated the gauge and waa laa, works like a charm. Now I have a 65 dollar VSS I can't use, yay!

Ha-ha, thanks for all the help.