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ess/cps unplugged at ecm??

H

heshhash

NAXJA Forum User
Location
Proctor, MN
i have a 1989 2 door cherokee limited with 4.0/aw4/242. i was under the dash installing a remote start/remote entry unit, and while fishing wires through the firewall next to the ecm, i notice 2 wire have been removed from the ecm. going off the wiring diagram in my paperweight chilton, they appear to be for the engine speed sensor. Could anyone explain why someone would do this, and how would that affect the vehicle? i've been searching and reading for 3 days and i am getting more confused the more i try to search and read... Thank You for any help, its greatly appreciated~
 
Seems I remember a technical service bulletin that replaced the wires that go to the CPS. Probably nothing to worry about if everything is working correctly.
 
i scoured through the bulletins, i found nothing in regards to that. i am not even sure what this sensor does, or how it would affect the vehicle... i know i have some cold start issues i'm troubleshooting, so i have no clue if this is related, or just my paranoia...
 
the CPS -crankshaft position sensor- is the main sensor for ignition timing. It 'tells' the computer where cyl #1 TDC is so it can trigger ignition spark accordingly. It also uses the sync sensor aka cam sensor aka CMP to trigger the injectors.

Found the bulletin
Chrysler service bulletin 18-51-88
 
/light bulb blinds me~
that explains alot! it would appear someone has done this. it explains the extra plug in connector on the intake that is not in use... i do know from the hard way that the sensor is working now that i know what it does, whomever did this on my jeep left the new connector down by the front driveshaft and i would up on the side of the highway when it got caught/(
Thank You for the help sir, much appreciated~)
 
What is the pin number(s) on the ECU?

If it was the CPS, engine speed sensor, the engine would never ever start.

Did this one have Cruise at one time? It might be the electronic speed sensor coming off the speedometer cable sensor under the dash.

Pictures might be a good idea!
 
Ecomike said:
What is the pin number(s) on the ECU?

If it was the CPS, engine speed sensor, the engine would never ever start.

Did this one have Cruise at one time? It might be the electronic speed sensor coming off the speedometer cable sensor under the dash.

Pictures might be a good idea!
Click to expand...
:confused:

Did you read the bulletin I posted?
 
dont know pin numbers, i went off wire colors. i am assuming digger was right and someone did the service upgrade... it does have cruise, but it is non operational... another note leading me to believe they did the service is the hole in the firewall is in the exact spot the bulletin calls for, and the rubber grommet on the wires wasnt pushed in... when i can get under the hood i just need to varify these findings...
 
Last edited:
Digger87xj said:
:confused:

Did you read the bulletin I posted?
Click to expand...

His first post makes it sound like there are NO WIRES, old or new at the CPS input to the ECU. The patch does not eliminate wires from the CPS to the ECU.
 
my first post i did not know of the tsb, so i had assumed the wire had been removed, but after reading the tsb, everything fell into place, sorry for the confusion
 
So there are two cut wires, and two new wires at the same pin out on the ECU?

The problems down by the drive shaft are usually the O2 sensor wires getting eaten by the drive shaft.

What kind of cold start issues are you having?

heshhash said:
my first post i did not know of the tsb, so i had assumed the wire had been removed, but after reading the tsb, everything fell into place, sorry for the confusion
Click to expand...
 
Ok, i was able to get under dash and vehicle to confirm diggers initial assesment in regards to the TSB. Whomever performed it never ran the connector back to the intake, they let it dangle next to the front drive shaft, it got caught and disconnected leavin me on the highway... I have reroute it temporarily till i can put it back properly. As far as the cold start, im not concerned till i replace a couple broken sensors and deal with more safety related problems i dont have funds for.
 
heshhash said:
Ok, i was able to get under dash and vehicle to confirm diggers initial assesment in regards to the TSB. Whomever performed it never ran the connector back to the intake, they let it dangle next to the front drive shaft, it got caught and disconnected leavin me on the highway... I have reroute it temporarily till i can put it back properly. As far as the cold start, im not concerned till i replace a couple broken sensors and deal with more safety related problems i dont have funds for.
Click to expand...

Instructions in the bulletin suggest cutting off the plug.
 
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