cps changing tips

[tugalo]

88 MJ 4.0 - Working on a no start/no spark condition and had no signal from the cps.  Time to change it after 33 years.  I was having trouble manipulating the long extension set-up so i took a 3 ft 3/8 inch dowel and whittled the end square to make it fit a 1/4 inch socket.  Much lighter and long enough to easily reach the cps bolts.  Another problem was that the bolts went too far down into the socket and did not have enough length to catch the threads, so i cut a small block of wood and pushed it into the socket to effectively lengthen the bolt.  Worked like a charm.  Good .5V signal from the new cps, but it did not solve my problem, so now I'm looking into the coil and ignition module.    Have done most of Cruiser54's tips but may have to look into the harness splicing of all the sensor grounds.  Any tips appreciated.

[Cummins93]

Wobble extension kit from harbor freight. Great for the CPS also good for the lower intake/exhaust bolts.

[Ωhm]

Using a voltmeter or 12vdc testlight (preferred) check for B+ on the following pins (use battery negative terminal for ground):
D1_5:  B+ (Hot at all times)
D2_4:  B+ (Hot during KEY ON/CRANKING).
D1_6:  KEY ON (B+ (Hot for 2-3 seconds)) or CRANKING (B+ (Hot during CRANK)).
 

 

[omega_rugal]

so you went through all the trouble of changing the cps before testing if it was the culprit

 

what do i tell you

[Pete M]

16 minutes ago, omega_rugal said:

so you went through all the trouble of changing the cps before testing if it was the culprit

 

what do i tell you

 

the first sentence says he had no signal from the sensor.  I'm assuming that means he tested it and it was dead. 

[cruiser54]

Here's a little trick to keep from dropping the bolt. 

[tugalo]

Thanks. OHM for the tips, I was poking around with my meter and checking for power at the diagnostic connectors and the connectors on the ignition module, did not find any problems, had 12V where it should be. The 5V on the small connector at the ignition module puzzled me till I realized - 5V logic.  Swapped relays around.  Pulled the coil and cleaned the contacts, coil measured 45-50 ohms across the primary.  So, I put it all back together and just for the hell of it hit the key and it started.  Loose connection maybe or corrosion on the contacts, but i did not see any.  Anyhoo, it's running for now, will probably strand me in the boondocks somewhere tomorrow.................

[Ωhm]

1 hour ago, tugalo said:

Swapped relays around.

 

This makes me wonder.

[tugalo]

Think it might be a bad relay?

[Ωhm]

I was just thinking swapping relays is a method used for troubleshooting. Your testing on the D1_D2 connector should have proved out the Fuel Pump Relay. Maybe cleaning the coil contact did more good for ya.

[omega_rugal]

22 hours ago, Pete M said:

 

the first sentence says he had no signal from the sensor.  I'm assuming that means he tested it and it was dead. 

 

weird that a relay AND the Cps went out at the same time, but its fixed so who knows

[omega_rugal]

i always wanted to cut a windows in the firewall where the cps sits so if ever fails it could be changed from inside