It could be that the connection is hanging up in the switch.

You refering to the orange and red fused together in the ignition switch?

I did check the computer or ECU and found nothing unussual

How would I test to see if the oxygen heater has no power during closed loop?

Dont know if you've seen this but page 41 talks about the o2 sensor and its relation with the ECU.

https://drive.google.com/file/d/0B7L...lQYl9vR2c/view

I'm kinda like that as well and somewhat dyslexic.

 

Probably just outside of the switch. A possibility anyway.

You should have some pointed probes with your mutimeter. Poke the positive probe into the orange wire at the sensor and ground the negative. When the heater's going (open loop) you'll see 12 volts. In closed loop it should be zero. It's good practice to patch the holes when you're done probing circuits.

Right. The ECU does not PROVIDE power. It will trigger the relay so it will Open and the power to the heater should cease.

 

The issue I see with that test is the constant 12v to the sensor

 

do you guys have the Renix Fuel Injection Manual in PDF form?

Page 40 explains the O2 well.

 

That's exactly what we're testing. I believe that even with the jumper in there (because it's on the ground side of the coil) the heater will turn off in closed loop (or at least once it hits ~1500 degrees).

 

I got the one that's missing page 59. Looks like page 41 has the O2 stuff.

I wonder if page 59 is the one where they tell you when it would be a good idea to change the wires around on the AC Relay...

 

ECU shuts off O2 heater based on the signal from the O2 sensor.

I have that manual in PDF form if you guys want it.

PM me your email address if you do.

 

Sure thanks! Would help immensely when doing a search.

 

Send me a PM with your email address.

 

Strange the fuel injection manual is missing page 59.
Wonder why, whoever wrote the manual would give a reason for switching the AC wires. A factory work around maybe? Not to brilliant wiring creation on their part.

On my way to the Junk Yard... hopefully some clues today.

 

Want a PDF manual?

 

I got the one that's missing page 59. Looks like page 41 has the O2 stuff.
I wonder if page 59 is the one where they tell you when it would be a good idea to change the wires around on the AC Relay...

Maybe I'm missing something regard your post on the fuel injection manual missing page 59 to dave51.
That's the PDF I'm referring to.

 

Struck out today at the junk yard on getting the relay holder off of the 90 Renis that I was going to use for referencing the wiring on my relay holder in order to make sure my wiring was correct or not.

The outfit with the 90 Renix that I was at last week when I was looking for a sensor, they have two yards. Since they were short handed today the yard with the 90 Renix was closed today.

Nutty way to run a business. Last week they had 1 person running that yard (their most profitable yard), and today they had 4 people running their other less profitable yard. And it had no Renix jeeps.

They said that they may or may not open that other yard (most profitable), tomorrow or on Monday. Said I would have to call tomorrow and Monday to find out if they'll open that yard.

No other yards in my area have an 87-90 Renix. Those Renix jeeps are becoming extinct real quick.

Turns out, yesterday was cleaning the garage and found a new Bosch 12009 sensor that I had forgotten about that I bought on ebay last year and hadn't returned. Reason I hadn't used it was because I thought it was the incorrect sensor due to the parasitic draw. Off course it turns out that I did have a wiring issue and parasitic draw was not the fault of all those sensor I had tried.

 

Installed new o2 sensor. It tested 5-6 ohms.
All relays in place including jumper wire.
Connected volt meter to o2 plug power wire and got a reading of 12.45 v with key off.
Once the key was turned to on position, engine off, power to o2 went to 0v
After starting engine still no power to the o2.
According to the mt2500 engine would go open/closed loop for the first 30-40 seconds (with 0v to the o2 during open and closed loop). LTFT would bounce between 128 and 255
After the first 30-40 seconds of engine running it then stayed in open loop. Still 0v to o2. LTFT stayed at 128.
Every time the engine would go into closed loop the RPM's would drop and then idle normal upon open loop.

 

Yay! The heater's off!

But right now I think the jumper wire is causing the fuel pump relay to also turn the heater off. Pull the jumper, turn the key to on and see if the heater still has power.

That jumper is going to have to eventually come out because right now when the engine is running the heater is NEVER on.

Yes.