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George H.
George H., Hyundai Technician
Category: Hyundai
Satisfied Customers: 18591
Experience:  Hyundai Gold certified, ASE Master tech 15+ years
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2007 Hyundai: Van..000 miles..It had front end damage..wiring harness

Resolved Question:

I have a 2007 Hyundai Entourage Van with 28,000 miles. I purchased it as a repairable. It had front end damage which included minor damage to a small part of the wiring harness. I have checked the wires extensively before putting everything back together. I am not getting voltage to #13 & #14 fuses in the fuse box under the hood. These are the fuses for the up stream and down stream O2 sensors. Since they are not working I have a check engine light on related to those sensors. Why no voltage to the fuses?????? What is my next step?
Submitted: 6 years ago.
Category: Hyundai
Expert:  George H. replied 6 years ago.

Hello I will help you with your question,

 

The O2 UP and O2 DOWN fuses are fed from the main relay contact which also feeds the INJECTOR fuse so if you have power to the injector fuse the main relay is closing and the fault is between the main relay and the fuses.

 

If you do not have power to the injector fuse then the main relay may not be closing.

 

Does the van run?

 

 

George H. and 5 other Hyundai Specialists are ready to help you
Customer: replied 6 years ago.
The Van is running great. Is the main relay in the fuse box? What do I do to check between the main relay and the fuses in question?
Expert:  George H. replied 6 years ago.

If there is a problem between the main relay and the fuses the FAM (Front Area Module/fuseblock) will need to be replaced.

 

Check for continuity with the battery disconnected between the main relay contacts and the O2 fuses. Seee the diagrams below for locations. Follow the "D" arrow from the main relay to the O2 fuses

 

Click here

 

And here

 

And here

 

 

Let me know what you find

 

Thanks

 

 

 

Customer: replied 6 years ago.
How do I check for continuity? Do I use an ohm meter? And where do I place the leads?
Expert:  George H. replied 6 years ago.

You do use an ohmeter to check for continuity,

 

Pull the main relay and look at it, find pin #87 and measure that pin socket for voltage, if you have 0 volts then switch to ohms and measure between pin socket #87 and both of the O2 fuses.

 

You should have 0 ohms or close to it.

 

The main relay is the large white one and should be marked on its side or bottom with the pin numbers.

 

What you are looking for is an open in the FAM (fuse block) if it is open you will have to replace the FAM.

 

 

 

 

Customer: replied 6 years ago.
How do I disconnect the battery between the main relay and the o2 fuses. Do I just pull the relay and pull the O2 fuses?
Expert:  George H. replied 6 years ago.

You can just pull the main relay, you caught me on the way to bed so if you are going to be working on this tonight all you have to do is see if you have a complete circuit between the #87 pin of the relay and the two O2 fuses. If you do not have a complete circuit then there is an open inside the fuse block and the fuse block will have to be replaced.

 

 

 

 

George H. and 5 other Hyundai Specialists are ready to help you
Customer: replied 6 years ago.
I tested the voltage from pin #87 to each side of the O2 fuse and I got 12.5 volts on all positions. I tested for ohms and was not able to get any reading on any positions. I had repaired some slightly damaged wires in the wiring harness originally but I think I made good connections with the 3-4 questionable areas. I also initially blew the 150 amp fuse that goes to the fuse box and then replaced it. So, do you still think the fuse box is bad?
Expert:  George H. replied 6 years ago.

I am not sure where you are measuring the 12 volts from pin #87 to the O2 fuses?

 

Does pin socket #87 have voltage with the main relay removed? If so how about pin socket #30 on the relay?

 

You should not have power on the relay pin socket with the relay removed. The O2 fuses are fed when the relay closes so we need to be certain of the readings. The FAM is expensive so measure twice.

 

Once you have the relay socket identified according to the second diagram I posted above then use your Ohmeter to see if you have the same reading between that pin socket and the O2 fuses as you have when you touch the meter leads together.

 

Let me know so we can confirm if you need a fuse block

 

Thanks

 

 

Customer: replied 6 years ago.
I re-checked my voltage at pin #87 and the two fuses for the O2 sensors. I had zero voltage and when I switched to ohms I also had almost zero (1.0). I must have not had pin 87 the last time I did the test. So, where do I go to now? Does this mean the fuse box is ok?
Expert:  George H. replied 6 years ago.

Ok if you have no voltage on the pin socket #87 and have a complete circuit to the fuses then you need to check the fuses again for voltage with the engine running. You can also test the Injector fuse for power to verify that the main relay is closed but the engine will not run with the main relay not closing so you have to have power tot he injector fuse but the injector fuse and the O2 sensor fuses all are fed power from the same point off pin #87 (shown as "D" in the wiring diagrams) so they all should have power with the enginne running.

 

Let me know what you find

 

Thanks

 

 

 

 

 

 

Customer: replied 6 years ago.
I measured the voltage with the engine running and no voltage reading on the two O2 sensor fuses. But the funny thing is I could not get a reading of any voltage across any of the fuses in that box, including the injector one. The van runs great so the injectors have to be working. What's the deal??
Expert:  George H. replied 6 years ago.

I suspect that you are not measuring correctly.

 

You need to put one of the meter leads on a clean ground, battery negative terminal is best. The other lead is used to probe for voltage, start at the positive post of the battery to confirm the meter is working (the leads do break over time) and with the meter set to DCvolts you should see 12.6 volts at the battery with the engine off.

 

This is why I prefer a 12 volt testlight for simple voltage tests.

 

Let me know what you find

 

Thanks

 

 

Customer: replied 6 years ago.
I think you may be right. In the past I was placing both probes across the same fuse (i am now guessing this was wrong). This time I pulled the main rely and placed one probe on the O2 fuse and one on the negative battery terminal and I did get 12.45 volts. I got the same for both O2 fuses. When I pulled the main rely and placed one probe in pin #87 and the other on the negative battery terminal I got no voltage. Sorry for being so poor at electrical but that's why I ned help. What now?
Expert:  George H. replied 6 years ago.

If the fuse is hot then a reading of 0 volts with the leads on both pins on the back of the fuse would indicate that the fuse is good but if there is no power to the fuse it would indicate nothing so you have to estabilish that you have power to the fuse first

 

It sounds like you have power to the O2 fuses so check at the O2 sensors. So what code are you getting again?

 

 

Customer: replied 6 years ago.
I am getting two codes -- P0037 and P0051 which are the codes for the two O2 sensors. I can't remember if I checked the voltage at the sensors but I will tomorrow.
Customer: replied 6 years ago.
I am getting two codes -- P0037 and P0051 which are the codes for the two O2 sensors. I can't remember if I checked the voltage at the sensors. I think that I did but I will do so again tomorrow and let you know. Thanks for all the help.
Expert:  George H. replied 6 years ago.

OK your next place to check for voltage is at the sensor connector, check for resistance of the heater element in the sensor (about 10 ohms) then make sure you have a continous piece of wire back to the PCM.

 

Let me know how i can help

 

Thanks

 

 

Customer: replied 6 years ago.
I'm back. I have been consumed with other cars so it has teaken awhile to get back to the van. I tested the ohms on the upstream O2 and I got 17.75 ohms. On the down stream O2 I tested for voltage and from the blue wire to ground I got 14.45 volts. I tested for voltage on the plug side that goes toward the fuse box. What's next?
Expert:  George H. replied 6 years ago.

Concentrate on finding voltage and ground at the sensors.

 

Check the blue wire at each sensor connector for power to a clean metal ground with the key on, next move the meter lead from the metal ground to the pink or pink/black wire which provides ground from the computer. You should have the same reading.

 

 

Let me know what you get

 

Thanks

 

 

 

Customer: replied 6 years ago.
On the downstream O2 sensor I get 12.45 volts from the blue to the pink, 12.45 v from the blue to the brown and 6.75 volts from the blue to the white wire. What next?

should there be any voltage readings on the upstream sensor?
Expert:  George H. replied 6 years ago.

DO NOT MEASURE ANY WIRES EXCEPT THE ONES I DESCRIBED YOU CAN DAMAGE THE COMPUTER!

 

The upstream sensors will have the same setup as the down stream so you should have the same readings. There is one sensor that has a pink/black wire rather than the pink so use that one. All the sensors have the blue power wire.

 

Once you measure the power and ground at each sensor harness side move to the coresponding pins on the sensor side of the connector and measure resistance. DO NOT MEASURE RESISTANCE ON ANY OTHER PINS YOU CAN DAMAGE THE SENSOR!

 

Let me know if you find anything that does not show power and ground on the harness side or is out of range on the sensor side.

 

Thanks

 

 

 

 

Customer: replied 6 years ago.
On the downstream I get the 12.45 volts from the blue to the pink wires. And on the sensor side I do not get any reading for resistance. Is the sensor bad?
Expert:  George H. replied 6 years ago.

The sensors should have some kind of resistance from where the blue wire and the pink wires would plug in so make sure you are on the right pins on the sensor connnector and are you seeing 0.0 or OL for the reading. Test by touching the tips of the meter leads together. This is a digital meter?

 

 

Customer: replied 6 years ago.
It is a dighital meter. The meter appears to be working but I get no reading whatsoever on the downstream, sensor side O2.

The upstream O2 I get the proper readings on voltage (12.45) and ohms 10.5.
Expert:  George H. replied 6 years ago.

Ok the down stream should have the same readings as the upstream so the heaters are open in the downstream sensors.

 

Sorry but the only thing you can do is replace the sensors.

 

 

George H. and 5 other Hyundai Specialists are ready to help you