I have an 87 4.0l and was just curious what the two ports are for next to the relays? Sorry no picture. Thanks

 

If your talking about the 2 Yellow Test Ports, one is small and the other is larger... i really don't know.

I noticed them a few weeks ago on my friends '88, and i wondered the same.


Sorry i can't help, i just wanted you to know you're not freakin' out!

 

They are what you said, just that. Scanner plugs into those ports for some serious pre-obd diagnostic tests. LOL I don't have the pleasure of plugging into many of those models anymore but that is what the plugs are for.

 

I've plugged into them before with a snap-on scanner. Good for reading sensors but you won't get codes.

 

The Renix test ports are not OBD 1, You can use them to test your system with a digital volt meter and a factory service manual. Testing using the test ports can save time and labor of testing your sensors without disconnecting and back probing things like MAP sensor etc. I found that out and am doing the same thing currently on my '88 XJ. However I am fortunate to have access to my buddies SNAP ON diagnostic scan tool with built in service manuals which walk you through each pin on the test ports! The tool is rather expensive though!

 

the older snap-on model was around $2000 in 05 now it's discontinued But I still use it on older vehicles up to 08

 

Always wondered but finally asked. Any write ups on how to use them with a volt meter?

 

you can get some information from them like that status of your fuel trims and whatnot. i have an '87 XJ with the 4.0 as well and i hooked into mine with a Modis scan tool from Snap-On and could get the status of my fuel trims and a few other things. but "itzdan" is right, you wont pull any codes.