I washed my engine bay the other day and think I shorted out the tach in my 91 DA. I have an aftermarket tach wired into the distributor harness via a t-tap. I'm wondering if water got in it when I washed the engine down. Now my factory tach sits at 0 RPM and my Auto Meter one is pegged at the red line (that I set). Now and again when I hit a bump the stock tach will jump and the AM one will drop to 0 for a second, then pop back up to 7k. I checked all my fuses and connections and they look good. I'm worried I shorted something inside the distributor for both tachs not to work. Any ideas?

 

well, check out the t connection, and make sure you didnt break that wire.. that happened to me.. i ended up just taking the tap out, wiring them all together, and soldering it, and sealing it..

If you got water in your dizzy, you could have trashed your CPS, which would make your tachs not work, and you cant really replace those.. i mean, you can, but they are difficult to get to..

ALWAYS COVER ELECTRONICS WHEN WASHING.. DSM's are notorious for getting water in the CAS, and causing it to fail..

Bust out the manual, and check the resistance on that sensor.. i have never done it, but im sure there is a way to test to see if its any good..

Try hooking a volt meter up to the tach signal wire, and start the car.. if you see voltage being generated, and it varies with engine speed, then it should be good... if not, then your CPS is toast

 

I put a volt meter on the wire, it seems to stay around 13.5 V. I moves around a little between 13.4-13.6V while idling. Revving doesn't seem to change the voltage much, it went to around 13.2V. I don't have a book to look up specs, maybe I could find something on Alldata. I don't know my abbreviations so well though, what is a CAS or CPS?

 

CPS.. a CAS is on DSM's.. lol.. they both do the same thing.. just read cam position...

If it didnt move, it looks like you got a bad CPS... I think that is what its called on a honda.. Cam position sensor.. It should move more than that..

other than your cam sensor, i dont see what else would short out both gauges..

 

I would think a burned out cam position sensor would cause running problems. The car runs fine, just no tach. It is a OBD-0 car though.

 

mmm.. idunno.. there are 3 different sensors in the dizzy, all of which control timing.. I mean, maybe this one sensor, all it does is just read signals for the tach... i have never had one burn out on me, so i couldnt say.. I would assume so, but i have seen these cars run just fine with ALOT of **** being screwed up.. haha

I would go over ALL of your wires, from tach to dizzy, again, and make sure they are all connected, and all of your grounds are secure and correct.. i still think its the sensor though.. i mean, did you cover your dizzy? what all did you clean? if you got water in the dizzy, it could for SURE cause that..

take off your dizzy cap and check for moisture.. also, see if you anyone else you know has a spare dizzy that you could try on your car, to see if that changes the situation.. if it works with another dizzy, then that sensor is dead, and needs to be replaced, most likely by getting another dizzy.. unless someone here knows how to change those damn things.. lol

 

lmao They do run pretty well even when screwed up. The good news is I just remembered where I bought my distributor and it's still under warranty, so I'll probably just swap it out one day soon and see what happens. And no, I was stupid and in a rush and didn't bother to cover the dizzy, against my own better judgment. }:-( All the wires are good, so like I said, I'll just swap in a new one for free within the next few days. Thanks for the help! Anyone else who wants to add something though, feel free! I'm always down to learn!

 

for sure.. lol.. just cover it next time.. those things are PRICEY.. lol

swap that puppy out, and that will probably fix it..

 

So this is weird. I let the car sit all day yesterday, and then when I started it today the factory tach started working again. The Auto Meter tach worked for about 10 seconds and then pegged out at the shift point again. Any ideas anyone? I'll probably still swap out the dizzy soon just to be safe.