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Grounding question?

R

Reclipse

NAXJA Forum User
Location
Aurora, CO
I have an 87 cherokee, Renix, 4x4, 234,xxx miles

I was just wondering was it normal to have the negative cable go straight to the block? I have never seen this on any other vehicle before and if this was a factory thing or if the owners before thought it would be easier this way.

When I was testing the TPS ground and my meter should have read zero(please tell me if I'm wrong), but it didn't, it showed some resistance as with everything else i tested for grounding, including the actually engine. This could be all my problems, cause all my sensors tested out fine, except my oxygen sensor.

Any thoughts are always welcomed...
 
Hallo. On my '92 a ground cable is running from the -battery post to the dipstick console on the engine block.
And one is running from -battery to the inside of the fender.
There is also one braid cable from the engine head to the firewall. Good condition is important!
'92XJwim
 
Last edited:
Reclipse said:
I have an 87 cherokee, Renix, 4x4, 234,xxx miles

I was just wondering was it normal to have the negative cable go straight to the block? I have never seen this on any other vehicle before and if this was a factory thing or if the owners before thought it would be easier this way.

When I was testing the TPS ground and my meter should have read zero(please tell me if I'm wrong), but it didn't, it showed some resistance as with everything else i tested for grounding, including the actually engine. This could be all my problems, cause all my sensors tested out fine, except my oxygen sensor.

Any thoughts are always welcomed...
Click to expand...

Every conductor has "some" resistance. Please state the magnitude. It should be less than an ohm if your meter is accurate and calibrated for the test leads.
 
I saw the braided cable to the firewall, and the regular one to the dipstick. But there is no cable running from the battery to the body, that is what is wierd for me.
 
I belive it was 6-8 ohms, sometimes it went down to 4, but for the most part it stayed around 6-8. When I tested a working car that had no issues, it tested close to zero, if not zero itself.
 
Hallo. You can always place an additional ground from the battry to the chassis.
Resistance in Ohms are difficult to reduce. Cleaning of the contacts and surfaces are important to have a low resistance.
The use of dielectric grease against corrosion is also advisable.

click for bigger and other pic.

wim
 
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I have the negative going to my block and body right next to the battery(as the above pic). I thought going right from the battery to engine block was normal.
 
Reclipse said:
I belive it was 6-8 ohms, sometimes it went down to 4, but for the most part it stayed around 6-8. When I tested a working car that had no issues, it tested close to zero, if not zero itself.
Click to expand...
way, way too high - your suspicions are correct. Even with a non calibrated meter that reads 2 ohms or so with just the probe leads that is way high, clean/tighten the connections or preferably replace the stupid braid strap with a real wire - something like 4 gauge or thicker in my opinion. Every ohm counts on grounding straps, with 6 ohms there, it only takes a few amps before the grounding strap has so much voltage across it (a significant fraction of the total battery voltage) that it might as well not be there!
 
Yeah, I'm gonna redo my grounds through out the jeep, even by the comp. I figured it needs it, Im just hoping this solves a lot of my problems. Thanks guys!
 
B- to block is correct/OEM. Adding an additional ground from the battery to fenderwell, or from the block to the unibody is a good idea. Replace the braided ground strap from the back of the head to the firewall with a cable, those braided straps deteriorate.

Clean the ground surfaces with sand paper or a dremel tool, then treat the bare metal with a commercial corrosion inhibitor (any paint dept/hardware store) and make sure the connections are tight.

There should be three ground wires to the dipstick tube--grounds for the ICM, the ECU, and the O2 sensor--very important grounds!
 
IMO, the Batt to engine is just a dumb design, its just a big loop with poor contacts and it really only has on main way to have a good ground. I'm gonna redo all those plus add the strap to the batt.

Joe, do you think this could cause my running rich, hiccup when idleing and stalling when pressing the gas when its warming up. I have tested all the sensors except the O2 sensor, and all these are still there, its slowly getting better, but the smoking is the thing that really irritates me. Im just lost on what else can cause this. the smoke is a greyish smoke that likes to linger. You can smell the fuel in it, thats why I believe its a fuel issue, that and very poor milage.
 
Reclipse said:
IMO, the Batt to engine is just a dumb design, its just a big loop with poor contacts and it really only has on main way to have a good ground. I'm gonna redo all those plus add the strap to the batt.

Joe, do you think this could cause my running rich, hiccup when idleing and stalling when pressing the gas when its warming up. I have tested all the sensors except the O2 sensor, and all these are still there, its slowly getting better, but the smoking is the thing that really irritates me. Im just lost on what else can cause this. the smoke is a greyish smoke that likes to linger. You can smell the fuel in it, thats why I believe its a fuel issue, that and very poor milage.
Click to expand...

yes, a poor ground can cause big problems on a computer controlled engine.
 
That is really the only thing that makes sense, I have been chasing this smoking problem for some time. Everything test out just fine, but a few of my problems exist no matter what I do to the jeep, its been baffleing me, and very frustrating. I mean it runs decent, not enough to pass emissions, but it just seems to be an ongoing problem where nothing changes the effect, if it does its very little.
 
have you tested the egr valve/solinoid/transducer?

also, with the ground strap on the head to firewall, i found it to be much easier to just add a new ground strap on the closest stud next to the oem strap on the head. the nut holding the oem strap to the head was on real tight and a little rusty so i didnt want to take a chance of snapping the stud off the head. the oem strap is also know to just crumble into pieces when disconnected although it visually looked good.

i also run additional grounds were i can. battery to radiator support and one from the alternator body to battery. some people also run a new ground to the tps.
 
The OEM braided strap, much like the "armored" wire-wrapped steel brake lines, appears almost to have been designed to collect saltwater and rust out ten times faster than anything else.
 
kastein said:
The OEM braided strap, much like the "armored" wire-wrapped steel brake lines, appears almost to have been designed to collect saltwater and rust out ten times faster than anything else.
Click to expand...

So, so true. :cheers:
 
Thanks guys, Im gonna redo pretty much everything, and give you guys the results. I hope they turn out like I am hoping. Which would include offroading very soon after!!!!

As for the egr, selanoid, and tranducer. I replaced the egr with a working one, the selanoid works just fine. The transducer, did the 87 come with that, if it did, where would it be located? If it is supposed to be next to the selanoid, it is not there as well as with the connectors.
 
Reclipse said:
Thanks guys, Im gonna redo pretty much everything, and give you guys the results. I hope they turn out like I am hoping. Which would include offroading very soon after!!!!

As for the egr, selanoid, and tranducer. I replaced the egr with a working one, the selanoid works just fine. The transducer, did the 87 come with that, if it did, where would it be located? If it is supposed to be next to the selanoid, it is not there as well as with the connectors.
Click to expand...

I believe only the 89-90 were blessed with the vacuum transducer valve.

Here is a good article on electrical in the XJ:

http://www.olypen.com/craigh/charge.htm
 
Reclipse said:
I belive it was 6-8 ohms, sometimes it went down to 4, but for the most part it stayed around 6-8. When I tested a working car that had no issues, it tested close to zero, if not zero itself.
Click to expand...

That is too high if your meter is reading correctly. If you short the leads together and it reads less than an ohm, you have a bad cable. Disco the cables and measure each one. Make sure the mating surfaces are clean with no oil.

A bad cable can cause all kinds of mahem with the system.
 
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