Intermittent check engine light with no/bad ground on pin 3 of chrystler 1 connector

Asked by Mar 20, 2017 at 06:50 AM about the 1995 Dodge Ram 1500 LT 4WD

Question type: Maintenance & Repair

I have a 95 Ram 1500 4x4 with the 5.9L gas engine and I have a check engine light  coming on intermittently . It is early 95 and has the Chrysler 1 diagnostic connector instead of the OBD 2 connector. It is also burning a lot of gas when the light comes on. This is causing the O2 sensor to read high watching an OHM meter.
  I cant get the scanner to communicate to see any data stream info on anything and the only way I can get codes is to cycle the ignition key off and on 3  times. I tried using a Tech 1A and an MT2500 and neither worked. I was told it was the map sensor or the EGR so I replaced them both but the problem remains the same. I hate throwing parts at one when the part measures within the correct parameters.
The only thing that I am coming up with is a ground problem at pin #3 on the chrystler 1 connector . I may have the pin # for the ground incorrect , but it is the ground pin on the connector that am measuring an open circuit. I added an extra ground to the engine and trans even though using an OHM meter showed there wasn't an issue with the ground to the chassis. It sets codes for the MAP sensor, IAC, EGR, VSS and Governor pressure solenoid--not the transducer. All of the sensors measure within tolerances  and governor pressure raised 1 psi. per mile per hour.
It doesn't cause trans to shift hard when check engine light comes on. I don't believe its and electrical problem because usually an electrical issue normally causes the trans to default to failsafe as soon as the engine is started. A performance/ration/hydraulic fault will trip the failsafe after it detects the problem after the 3rd time if I remember right.
The only thing left I can think of is the  ground in the computer. I cant find any info on back probing the wire to the proper pin on the computer going into it or coming out of it. I hate throwing another $125 or so at it . Do you have any info on ohm the computer/wiring or would you suggest trying the computer without verifying it.
I am sry about the lengthy diagnostic description and apologize if I confused you. I used to build transmissions but I got crushed against a wall by an unsafe worker steering a truck into the shop so I hope I got it right. I am on disability now and money is tight and hate throwing money at it that I don't have.

1 Answer

I would say if the 02 sensors reading high. Cadillac converter is stopped up. it will load up the great deal of gas when traveling. 3pin, might take it to advance auto parts and let them put there's on it to see if it is reading the same. Oct sensors usely wouldn't be showing up in less that your Cadillac converter is stopped up. What I would do, is take battery cables off for about 20 mins after you run it like going to town are to the store are at least 10 to 20 mile run. as soon as you stop back at the house, thin take them off for about 20 mins. Thin put ground on first thin hot. because if for say you spark the cable it will give it a false reading. thin after you run test. that should give you a true reading. 95 to 2017 lot of years for Cadillac converter not to be changed. usely won't to change every 5to6 years. thanks David Bigcountry Wardlaw,

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