MCCUTCHEON4

While using a Snap-on scanner this past week end the scanner would intermittently loose signal from the Jeep? We plugged into two other vehicles to test the scanner and neither of those dropped the signal. We double checked the under dash plug-in, it was good.


The scanner indicated a P0305 code when it did work.
I bought a remanufactured set of injectors that I should have by the end of the week and will try that but don't have a good feeling that they will
do the trick


It has a new coil pack and plugs.


I now also have an oil pressure gauge malfunction, it pegs itself at 80
psi and the scanner says it has 100 psi.


Any ideas?


Thanks,
Gregg

CCKen

Does it lose power or does it indicate it can't communicate?

How did you check the DLC? Just looking at it?

MCCUTCHEON4

The scan tool didn't loose power, it could not communicate.


We disconnected the connector, visually checked it to be certain there was no debris or damaged pins then plugged it back in making certain it was completely seated.


I have little experience with EFI, I'm just guessing you were referring to the under dash connection when you asked about the "DLC"




Thanks,
Gregg

freegdr

Change the oil pressure sensor....

CCKen

DLC stands for Data Link Connector.

The pin cavities in the DLC do get corroded. It appears as black or dark gray, and worse case, green. And, the pin cavities may have suffered damage from people shoving meter probes in them, causing them to be enlarged and making poor contact with the pins in the scanner plug.

You'll need to get a 10 X magnifying glass and a bright flashlight and look at each pin cavity. Look for enlarged pin cavities and the appearance of corrosion. Corrosin can be cleaned out using a tooth pic dipped in distilled white vinegar then poked around in the cavity (repeatedly). Followed by flushing with CRC QD Electronic Cleaner.

Enlarged cavities are a different story. You may try to pry them back together using a sharp tool.

Study this schemtic. It shows the pin cavities in the DLC and the basic function of each.

Note that pin cavs 7 and 8 are the SCI portals to the scanner. They must be clean and tight (see above).

Of course, pin cavs 3 and 11 must be clean and tight as well.

Cavs 4 and 5 are the ground for the scanner. They are located at the oil dipstick tube bracket stud.

MCCUTCHEON4

Ken,
I will check the DLC this Saturday.


Thanks,
Gregg

MCCUTCHEON4

freegdr,


Seems an odd coincidence that the oil pressure sending unit would fail at the exact time we plugged in the scanner. I will replace the sending unit
but have the sinking feeling that there is another reason for the gauge malfunction.


If I cycle the key on and off a couple times it will work correctly for a few seconds then I hear what sounds like a relay clicking and the gauge pegs
itself again.


This Cherokee has 81,500 miles on it for reference.




Thanks,
Gregg