Is there any other way to test the cas other than spinning by hand with the key to on and checking for spark?

 

At the moment, I don't have the FSM in front of me (I'm at Whole Foods drinking a beer), but I'm certain that the shop manual provides either the voltages or resistances at the connector. After all, it is only a Hall effect sensor consisting of two coils of wire that trigger the ignitor coils when the CAS fins are in close proximity.

 

Ok...the following info is from an old '86 Mazda FSM. I'm sure the CAS's are the same for all 2nd Gen's. Looking downward into the CAS electrical connector. First wire just to the right of the connector clasp is G2. Moving around in clockwise directio, we next have G1, then Ne1, and lastly Ne2. Top down view sort of looks like this where [C] is the connector clasp:

Ne2(R) [C] G2(G)
Ne1(W) G1(B)

Terminal G1 (B) - G2 (G), resistance 110-210 ohms
Terminal Ne1 (W) - Ne2(R), resistance 110-210 ohms

Where wire colors are:
B - Black
W - White
G - Green
R - Red

Also, if the fins on the shaft are broken, chipped, or bent than that's another problem.

Hope this helps.

 

the above is correct. if you spin it while checking you will see the resistance rise and fall, or if you check voltage, it will generate voltage too (i wanna say AC voltage, but don't hold me to that)

basically though, the ECU will fire the plugs if it has power and an RPM signal, so if there is spark the CAS works. i have seen a couple CAS's with bad connections at the connector, and the funny one only worked if i spit on it. for a couple blocks.

 

Actually, it would be considered pulsating DC because the time average voltage is some positive value between 0 and Vmax volts. An AC voltage changes polarity and would have a time average voltage of zero. Also, don't measure the resistance while rotating the shaft because you'll get an erroneous resistance value.

 

a lot of people believe they have a bad CAS when it is actually just that fouled 4 pin connector at the CAS.

i sold all 6 of my spare CAS in about 6 months, and it's not like i was giving them away... though in all my time working on these cars i never actually came across a faulty one, but then again i never lived out here where salt air eats everything, but the car still fires up, so...

most of the time when there's no injection or spark it's just a bad ground to the ECU on the engine, blown computer fuse in the cabin(short in the engine harness somewhere) or faulty coils/fouled plugs, less often than not is dirt/grease in that CAS connection(i just spray it with carb cleaner and blow it out with compressed air, plug it in and unplug it about 50 times and retry).

 

I'm installing a Haltech Elite cpu and I'm not getting an rpm reading from the ecu(in addition to no spark). I've spent a good amount of time on the phone with their support and have narrowed it down to the cas. -- wired up correctly, wires have connectivity from the cas connector thru to the ecu. tho, i haven't tried cleaning up the contacts on that connector. I'll give that a go.

 

Unplug the CAS at the CAS and the ECU and do a continuity to ground on each of the 4 wires. One meter lead to one of the CAS wires and the other meter lead to the battery ground (negative terminal) and if the meter rings out you have a wire which is accidentally grounded.

 

in recent years i tend to just want to hardwire the CAS and eliminate that connector.

 

New(rebuilt) CAS, still flaking out -- intermittent rpm readings.
Cut the connector, hardwired it. Works good now.

(Just to make sure I didn't blow $$$'s on the new one, I tried hardwiring the old CAS--still had an issue.)

It seems that when they rebuild it, they don't always swap out that connector which I guess could be the problem to begin with.

Maybe hardwiring the CAS (removing that connector) should a reliability mod on these 30 year old cars?

 

that connector is rather difficult to find, i looked all over for it though i found most of the other engine harness connectors. i've seen a few "rebuilt" CAS', all they are is bead blasted or painted, cleaned and inspected to be sure they are working, still just a used but clean part.

adjusting the air gap smaller for the sensors inside also helps with the signal quality.