Trucks a 93 auto. All factory. Have had it for about 3 weeks now Everything seemed to work and ran great. Out of the blue it lost od ac and voltage regulator. SoI set my air gap to .050 it was fine for a few days. It did it again out of the blue. 4 times I set it was fine. It got to where it didnt matter how many times I set it. It wouldn't go back. If I left it alone for a few hours. Everything would ne back to normal for awhile. So I put a new cps on it set the gap and now its doesnt recognize it all. I have power at the cps conection. On the female end. Just with test light not sure bout volts yet. Also did the pcm connector test. Bank one is hot all time and 9 is with key. Also the two grounds. Whats next? I cleant the terminals and ran new ground to the core. Im lost.

 

tighten the bulkhead wiring for main wiring going into cab.

 

I was thinkn something to do with intermeted loss of igntion. But I get power at the ecm plug as it states I should

 

still could be loose wires or maybe a loose ground ? even under dash .

 

Ok I see what your saying. But im still curious as to why seting the gap would set it back to normal again. Now thr trucks beem sitting since noon today. When I get home im sure it will be back to normal

 

The fault is random. Your "fixin'" probably had nothing to do with when it decided to work.

Leave the bulkhead connector alone. There is no connection in it that I know of that is related to this problem.

The CPS gets it's power from the PCU, and sends it's signal to the PCU, which controls all the functions that are intermittent. You're on the right track there.

There is a connection at the front of the engine, and another 10 pin connector block under the intake manifold between the CPS and the PCU. All that wiring must be in good shape for it to work.

Probing the connector to the CPS, the tan wire should be 8V. That is supplied by the PCU, and is shared by the VSS. If your speedometer works, it's probably OK.

The black with blue trace wire is the sensor return wire. It should be near ground. It goes through several connections back to the PCU, and is shared by almost all the sensors under the hood.

The grey wire is the signal. You should be able to see it pulse with a voltmeter while cranking the engine. Easily displayed, of course, with an oscilloscope if you have one. It should swing between near 0 and approximately 5 volts. I think it is a hall effect sensor, so it will switch when over the gap just like it was a cam switch, not sensitive to speed at all.

With this info, shoot the bugs out of the wiring harness, being careful not to make new ones in the process. I find a product called DeOxit D5, available at your local guitar center, or radio shack does wonders on corroded connections.

 

Sorry guys, reading this thread and can't figure out what the CPS is?

 

I assume they are talking about the crank position sensor

 

Thank you....makes more sense now.

 

Well I jiggles some wires after work last night. It worked. EverthIng was good all day. I started it around 15 or 20 times today. Well bout 15 mins ago I went out to check amd what do you lnow no charge!!

 

Now is there any chance a temp sensor of some sort is tied into any of this. I do notice sometimes my temp gauge will jump way up even under no load ay hiway speeds and then drop very quick back down to normal. Not long after it seems when the probs start and also when the truck is totally cooled down when I get off tonight therers like a 90% chance it will back to normal

 

The temp sensor would share the sensor return (ground)

Clean the connector for the TPS, and also the connector under the intake manifold with Deoxit. If that don't cure it, clean the connector on the PCU. Be sure to disconnect the battery before you start messing with that, though.

Also, look for any sign of green, or insulation bulging near the connectors. Someone may have pierced the insulation years back, and the wire is corroding inside.

 

Would the temp sensor being bad cause the cps to not get the correct voltage.

 

Sorry for all the posts buy I aslo notice when its not doing what its pose to the ecm Is making a very faint buzzing sound with the key on

 

Hey what do you its reading the cps now.