Originally posted by TurboBob
Hi,
Got your e-mail, but thought I'd reply here.
The Scanmaster design has not changed since it was introduced.
It has been an extremely reliable device with very few problems.
For all the units I have received for repair, most have been fine.
About 2 years ago we switched processors to an improved version that
is less prone to trouble if the ground is flaky. But, like all modern electronic
gizmos, good grounds are essential.
Since your unit is powering up and displaying "2.1" your power and ground
connections are probably fine. So it would seem that the datastream is not
making it into the unit.
If the unit is receiving data, one of the decimal points (the one at the far right)
will be blinking while the unit displays "2.1".
Since the data is essentially "ground pulses" you can verify that
the Scanmaster can receive pulses by touching the data wire to
ground after the unit has gone to sleep. If you touch the data
wire to ground while the unit is sleeping the unit should go through
the "2.1" sequence again looking for data.
The data wire in the GN's is orange, I think. So look at the back side of the
ALDL connector for the orange wire and use that pin to connect to the Scanmaster.
I have seen several cases of defective ECM's, The engine runs fine but no data
comes out. What happens is the low speed fan relay or the TCC solenoid shorts out
and kills the quad chip in the ECM. Plug in another ECM and still no data
(because you killed that ECM too....) I have a small pile of ECM's that suffered this fate.
So, the above said, I'd be happy to check out and repair the Scanmaster for you. No charge.
But try the 'touch the data wire to ground' test as a first step.
Post your results here. If you want to send the unit to me for checkout
let me know, I'd be happy to help in any way I can.
Bob