So I have a 91 Jeep Cherokee Sport and on Friday I was headed out to work and right as i pulled out of my driveway my jeep just died. No warning at all. I still had power but the Jeep would just crank and crank and crank, but not start. So I did some research and saw that the most likely suspect was the crankshaft position sensor. So I called the dealer ordered a part and it will be here on Monday. Through out the day I started to wonder if it could be something else and didn't want to wait till Monday after work to find out. So I decided to do the "key trick" to try and verify the code. So I went out to try it and noticed the check engine light wasn't coming on. So I pulled apart the dash to change the lamp out and noticed the lamp was still good. So just to be sure I pulled out one of the other lamps I could see was good and put it in the check engine light socket and it didn't work. I checked the copper contacts on the back where the sockets contact the copper strips and they all look good. So I bent the little copper wings on the part of the socket that touches the copper strips to make sure they were getting a good contact and still nothing. Next I grabbed my multimeter and on the copper strips I had 11.78 volts so I used my test light and it lit right up. So now im just at a loss because I have power there and have tested lamps and sockets that I know are good but when I actually put them in nothing happens. Any Ideas?

 

That's a strange one. Did you actually test the bulbs with an ohmmeter? That's all I can think of to try.

Love your sig line, BTW.

 

Yes I did they have continuity.

 

And I don't know if it helps but I tried to use the key yricl to get the code using a test lamp and it doesn't work to lamp just stays lit and doesn't blink.

 

The CEL may be switched on by the ground side of the circuit, like almost everything that is controlled by the PCM. Look for blown PCM fuses, or any other blown fuse.

 

did you have a ground circuit? have you checked the fuse for ecm/obd/diag i'm not sure what it would be classified under in the 91. you can always force a computer reset, disconnect the battery terminals and touch them together for 30 seconds. it may be possible in the worst case scenario that you may not have a bad cps but possibly a communication problem w/ the ECM. let us know what you come up with.

 

That's what I'm doing right now. Would a relay have caused this?

 

So I just finished checking all the fuses and relays and they were all good. I cleaned all of them up and put some silicone grease on all of them to be sure. When I use a mulitmeter it shows I have a ground and 12 volts. What should the ohm reading be for the cps with the round type connector? All I can find is for the older style flat connector.

 

If you have 12volts at the ground side, that means you don't have a ground. It's an open circuit, or an unswitched circuit.

 

I only show 12 volts on one of the copper strips for the check engine light not both.

 

Replaced the CPS still wont start. Any Ideas? Help....

 

When you turn key to run check engine light functions correct, your doing key on key off key on key off key on correct ?

 

Yes off not lock.

 

So I spent some time today trouble shooting and here is what I came up with. I checked that I have fuel flow by pressing the check valve and it shot fuel so I pressed it a few more times just to make sure there was no pressure. Then I turned the motor over a few times and checked again and i shot fuel again. I know most ppl dont like this method but it works for now. I used starting fluid to be sure and I still had nothing. So I started to look at the grounds and found the one on the engine block to be not the best so i took it off and cleaned them all off and put them back with some dielectric grease and put them back. Tried again and still nothing so I pulled a plug and instantly noticed it was all white ( I just replaced these last year). I grounded out one end and found there to be no spark when turning over the engine. I pulled the cap and the rotor was trashed along with the contacts on the cap. I also just put those in last year. So I have come to the conclusion that the bad ground led to the early death of all of these parts along with a distributor that appears to be the original. So Im going to replace all these parts tomorrow and see what happens.

 

So you have fuel pressure, but have no idea if it is the correct amount, plugs that look like they have been run lean, and a no start.

Do a tune up (fuel filter, plugs, wire, cap and rotor) and get a new cps.