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jeep xj 88 renix no power at o2 oxygen sensor

Old 09-02-2016, 05:00 PM
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Default jeep xj 88 renix no power at o2 oxygen sensor

hello,

i have read a lot of post and seen a lot of pictures but none looks like the one i have here.




what i understood from most pictures/diagrams i found the first relay closest to the battery should be the oxygen sensor heater relay but its not im pretty sure the first one in line closest to the battery is my fuel pump. which one would be the oxygen heater sensor relay ?
i dont not have an Air Conditioner its just 3 relays.

my problem is after testing the voltage on the connector down by the exhuast manifold oxygen sensor i get:

Orange and Black 4.7 volts (5 volts is good i read)
Orange and White 0 volts
Black and White 0 volts

im missing the 12-14 volts so some of these wires

so im asuming the relay doesnt work or no power to it, we having the key On engine Off is how i measured this..

is this relay fused somewhere ?

having all the relays out and key On and engine Off i get 12.25 volts on the first relay socket closest to the battery the 2nd relay socket i get some weird reading 1.6? something and the 3rd relay socket i get nothing at all.
not sure how to go about this.

does anyone know ?

thanks, marc

[edit] i have switched all 3 relays out with the first socket and i hear the fuel pump coming on with each on these relays makes me think the relays are fine

Last edited by LadyKenai; 09-02-2016 at 05:08 PM.
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Old 09-02-2016, 06:31 PM
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I'm pretty sure it needs to be running to power that 12V heater wire. Not sure why...could it overheat without hot exhaust flowing past it? In any case on renix it seems the fuel pump relay performs some of the tasks that an ASD relay does in OBD I-II, including powering the 02 heater relay when it's running. My messed up thread actually still has 02 info to be found> https://www.cherokeeforum.com/f2/ren...ce-rms-133153/

Do make sure you have less than an ohm or so of resistance between that ground wire and Batt.Neg. In Cruiser's tips he points out where a bunch of grounds meet at the dipstick mount stud. His links are in my sig allong with some other random renix stufff.
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Old 09-02-2016, 07:07 PM
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thanks for your reply

hmm ok i have to try this again with the engine running and see what i get then.

yes i forgot to mention i have done a lot of the cruiser54 ground refreshing on multiple points including the one you mentioned.
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Old 09-03-2016, 08:14 PM
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Note from DJ
I’m not sure if this information will help or not but this what it looks like to me.

Looking at the photo of your relay sockets the middle on is for the 02 relay because it is the only one that uses all 5 cavities. The one on its right appears to have a Black with white stripe wire going to it if so that is your B-Latch relay socket. The fuel pump relay socket will have a yellow wire an orange wire an orange with black stripe wire and a red wire. And you have no A/C relay socket that is why you only have 3 sockets.
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Old 09-04-2016, 02:33 PM
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Note from DJ
If you want more information please post back requesting it. Otherwise we will think that you solved your problem.
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Old 09-04-2016, 07:15 PM
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can you confirm the engine needs to be running to get the 12-14 volts on the o2 sensor on the exhaust manifold. we are having a lot of rainy days and im trying to tackle this in between the rain hoses, i will do get back on this
by testing with the digital multimeter i do get 11.45volts on the middle socket when the key is On and engine Off
having the black wire from the meter on the negative of the battery and the red wire from the meter in the middle socket (standing on the passenger side of the jeep looking down on the sockets into the left contact point of the relay socket) and my meter on ohm i get 4.1 ohm that seems a bit high for a ground. i doubled checked the ground wires at the disstick stud and cleaned them off again and looks good and clean. not sure where these socket the ground point is.

marc

[edit] maybe i am wrong but if this relay is powered on when having the key on the ON and engine Off shouldnt that lead the power to the o2 sensor ?

Last edited by LadyKenai; 09-04-2016 at 07:18 PM.
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Old 09-05-2016, 01:15 AM
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Note from DJ
I have an 88 so this is a schematic I have been working on for my 88 but I have not verified its accuracy.

You’re QUOTE “can you confirm the engine needs to be running to get the 12-14 volts on the o2 sensor on the exhaust manifold”.NO but with the key just in the on position engine off may be good enough.

You’re QUOTE “by testing with the digital multimeter I do get 11.45volts on the middle socket when the key is On and engine Off”. That appears to be correct.

You’re QUOTE “having the black wire from the meter on the negative of the battery and the red wire from the meter in the middle socket (standing on the passenger side of the jeep looking down on the sockets [this part does not make sense INTO THE LEFT CONTACT POINT OF THE RELAY SOCKET] and my meter on ohm I get 4.1 ohm that seems a bit high for a ground. QUESTION: Was it the middle socket or the left contact?

You’re QUOTE “maybe I am wrong but if this relay is powered on when having the key on the ON and engine Off shouldn’t that lead the power to the o2 sensor? It looks like it would if the relay was in place
IF YOU HAVE THE HARNES UNPLUGED FROM THE O2 SENAOR YOU WOULD HAVE POWER TO CAVITY [A] of connector C229 BUT I HAVE NOT VERIFIED THIS ON MY 88XJ.

But this is where I’m confused by my schematic cavity [A] of connector C229 will have battery voltage powered as long as the relay remains in the normally closed position and the C229 connector [B] is attached to a permanent battery ground which appears to me that will keep the heater on continually till the key is turned off or the engine is started and the ECU grounds the relay coil and the relay switches to the normally open position. This can’t be possible because the heater will burn out.

So as long as you have the harness unplugged from the 02 sensor I believe you are good to go on your test.

My question is why are you trying to test your 02 sensor?

Here is my schematic for what it’s worth it is still a work in progress!


Last edited by djgrayxj; 09-05-2016 at 09:55 AM.
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Old 09-05-2016, 04:12 AM
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thanks for your reply djgrayxj,

and sure appreciate the schematics i need to have a closer looks at this tomorrow.

the sensor looks really old im almost sure its been in there since 1988. after reading on the forum was adviced to be sure the wiring and right voltages are correct before even replacing this sensor.

excuse my english with naming certain parts, its this one:





the green circled one with the negative to the battery having the meter on ohms i get 4.1 ohm. im just mentioning this cause i thought it be helpful to give as much information.

marc
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Old 09-05-2016, 04:46 AM
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looking at your schematics i should have measured the relay connector number 85 with the meter on the negative terminal to see if the ground it good and not on 86 cause thats not a ground.

Last edited by LadyKenai; 09-05-2016 at 04:48 AM.
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Old 09-05-2016, 10:19 AM
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Note from DJ
Heated sensor lifetime is typically 100,000 miles (160,000 km).
Do you have any of these symptom?
Symptoms of a failing oxygen sensor includes:
Sensor Light on dash indicates problem
Increased tailpipe emissions
Increased fuel consumption
Hesitation on acceleration
Stalling
Rough idling

Here is some reading material for you if it's raining
TITANIA 0xygen Sensors Techtips
http://www.tomco-inc.com/Tech_Tips/ttt20.pdf
From about half way down column one of page two is related to Jeeps.

Please keep us post as to progress or lack of.
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Old 09-05-2016, 10:56 AM
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Factory recommended interval for the O2 sensor replacement was when the Emissions light came on.

Can't remember if it was 67K or 82K miles.
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Old 09-05-2016, 11:06 AM
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Note from DJ
Here is my guess as to the Figure numbers in the rainy day readying link I posted for you titled TITANIA 0xygen Sensors Techtips because they didn’t number them.

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Old 09-05-2016, 06:17 PM
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it seems like this sensor is way over due with 250k+

djgrayxj,
symthoms:
sensor light indication: No
increased tailpipe emissions: It smells like a lot of exhaust ? Yes
increased fuel consumption: Yes (im sure it did better on the gas 5 years ago)
hesitation on acceleration: Yes and No (lose a lot of power going up hill not really a hesitation tho)
stalling: Yes (that seemed to be fixed after i replaced the Crank Shaft Position Sensor, still tho it did stall one more time after this replacement not since a long time now been doing good lately)
rough idle: Yes (Definitely, switches from low idle almost to the point it wants to die to a higher idle that sounds more like a normal idle) the two differences between these idles switch from around each 10 secs

cruiser54,
• Emissions Control Timer, reached 2750 hrs 80.000 mls, removed (drivers side underneath dashboard next to the wiper interval, this emssion control timer was not hooked to anything)

djgrayxj,
thanks for the rainy day information i sure will add this to my collection of diagrams and schematics for this jeep to study this more.

this is what i find at my local store:
http://www.oreillyauto.com/site/c/de...2205&ppt=C0033

56$ hopefully will take these symthoms away or at least a part of it, its an old jeep and im trying to catch up with the maintenance.

marc

Last edited by LadyKenai; 09-05-2016 at 06:38 PM.
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Old 09-05-2016, 07:20 PM
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Originally Posted by LadyKenai;3300260[edit
maybe i am wrong but if this relay is powered on when having the key on the ON and engine Off shouldnt that lead the power to the o2 sensor ?
The SPDT relay gets tricky. It gets power in two places, can put it out 2 also, and do more tricks. No point in dissecting that now.

You might be over thinking it. We might have mentioned to spay the thing with PB blaster, liquid wrench or something sooner, in case it's gonna fight you. Spray it! Sooner the better. When you get your new one, chop the wires on the old and fit a 7/8 box wrench on it. Check the Jeep side wires right at the 02 plug, so you know the wires and relay are fine. (I believe it needs to be running to power the 12V heater wire.) Install the new and you are done. If there does turn out to be a problem with the heater power, then tracing it will make more sense.
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Old 09-05-2016, 07:44 PM
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thanks DFlintStone,
it sure is a tricky one and im not the only one that was confused.
i have checked closer on the sensor and even had it out with no trouble by just using a bigger crescent wrench for the first turn the rest just comes out by hand luckely. the sensor looks old but hard to tell for sure with all that heat it discolors fast i think.
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