Pulled some codes and everything is over max voltage? Whats that all about?

[BlueOvalStangGT]

Pulled codes on my car and got
118- Coolant Temp Sensor above MAX voltage/indicates below -40 degrees
123-TPS over MAX voltage
113- IAT sensor indicates open circuit/below -40 degres
337- EGR circuit above MAX voltage
539- Air Conditioning on during self test(it wasnt)
564- Fan Control circuit failure

Im guessing everything is related cause I dont think everything would read above max voltage at once. What could be the problem here?

 

[jrichker]

You have a broken signal ground or loose connection in the wiring harness between the sensors and the computer. Without a functioning ground for the sensors, the voltage output from the sensors goes high and stays there.

With the power off, measure the resistance between the gray/red wire and battery ground. You should see less than 1 ohm. Check the same gray/red wire on the EGR and MAP sensor. More than 1 ohm there and the wire is probably broken in the harness between the engine and the pin 46 on the computer. On 93 and eailer models, the 10 pin salt & pepper shaker connectors are bad about causing loose connections.

See http://www.autozone.com/servlet/UiB..._us/0900823d/80/1d/db/3c/0900823d801ddb3c.jsp for wiring diagrams.

 

[BlueOvalStangGT]

Where can I find these wires? I looked by the EGR and there were no gray/red wires and I cant reach my MAF>. Could this CE light be why my car is running horribly? Sometimes it wont idle, surges and stalls alll the time.

 

[jrichker]

Where can I find these wires? I looked by the EGR and there were no gray/red wires and I cant reach my MAF>. Could this CE light be why my car is running horribly? Sometimes it wont idle, surges and stalls alll the time.

Re-visit the link for the wiring diagrams. The diagrams & wire colors are for a 94-95 GT, which is what is in your sig.

All resistance measurements must be done with the power off the circuit.This avoids false readings and possible damage to the ohmmeter.

Check for less than 1.5 ohm resistance between the EGR & TPS using the gray/red wire. The gray/red wire connects to pin 46 on the computer and is connected to the EGR, TPS, ECT, ACT, & O2 sensors. The gray/red wire is the signal ground and MUST have less than 1.5 ohm between it and ground. If it is open circuited, the sensors don't function properly. Check the resistance on the gray/red wire between all these sensors and ground. You should see less than 1.5 ohm. More than that means a broken wire or bad connection. Be sure to try wiggling the wiring and connectors as you test them.

There isn't a MAP/BARO sensor on 94 and later models, that's my oops.

 

[BlueOvalStangGT]

Ok, im a newb at electrical stuff so lets pretend I KNOW NOTHING. I take my lil multimeter, swithc it to the upside down U thing, take the neg and put it on my battery ground and the pos to that lil grey wire at my egr/iat/maf. Right? If so I get nothing,

 

[BlueOvalStangGT]

r

 

[jrichker]

Ok, im a newb at electrical stuff so lets pretend I KNOW NOTHING. I take my lil multimeter, swithc it to the upside down U thing, take the neg and put it on my battery ground and the pos to that lil grey wire at my egr/iat/maf. Right? If so I get nothing,

Teaching the basics of electricty is beyond the scope of this forum.
Time to find/make a friend locally to help...

 

[BlueOvalStangGT]

Thats awesome.

 

[jrichker]

Ok, im a newb at electrical stuff so lets pretend I KNOW NOTHING. I take my lil multimeter, swithc it to the upside down U thing, take the neg and put it on my battery ground and the pos to that lil grey wire at my egr/iat/maf. Right? If so I get nothing,

Step 1.) Find the instruction book that came with your Multimeter. Read it and familiarize yourself with how it works and how use it. If you lost the book or didn’t get one with it, do a Google search on the web to find the manufacturer’s web site & download a copy of the manual.

Step 2. ) Make sure that you know what test lead plugs into which jacks on the Multimeter. There are usually several different jacks on most Multimeters, and they have different functions. Make sure that your battery(s) in the Multimeter are good: if you have any doubts, replace the battery(s).

Step 3.) Once you are sure that the Multimeter is functional and you have the leads plugged into the jacks for Ohms ( the upside down “U” symbol), do some simple measurements to make sure that you know how to use it correctly. Set the switch to the lowest range and touch the leads together: you should not see “nothing” but you should see 1.0-0.3 ohms. Measure a 60 watt light bulb: cold it will measure about 17.5 Ohms. It you measure it while it is hot, the reading will be greater.

Step 4.) Make several test measurements using the ohms function and the DC volts function. Remember all resistance measurements must be done with the power off the circuit. This avoids false readings and possible damage to the ohmmeter.. Repeat steps 3 & 4 until you are sure that you can do it without making any mistakes.

Step 5.) Then see http://www.autozone.com/servlet/UiB..._us/0900823d/80/1d/db/3c/0900823d801ddb3c.jsp and carefully study ALL the information under the Heading Chassis Electrical, Basic Electricity – Understanding & Troubleshooting

Step 6.) Go back and carefully re-read both of my previous posts and download and print the diagrams from the link posted. http://www.autozone.com/servlet/UiB...23d801ddb3c.jsp for wiring diagrams.

Step 7.) Apply what you have learned and make the test measurements using the information in the wiring diagrams & my previous posts. You will find either a broken wire or bad connection in the signal ground circuit between the computer pin 46 and the gray/red wire on the sensors you listed in your first post.

 

[BlueOvalStangGT]

. Set the switch to the lowest range and touch the leads together: you should not see “nothing” but you should see 1.0-0.3 ohms.

is that correct or is it 1.0-1.3?, thanks alot for the write up btw.

 

[jrichker]

is that correct or is it 1.0-1.3?, thanks alot for the write up btw.

one.point zero to zero point three - 1.0 to 0.3 ohms

 

[BlueOvalStangGT]

Ok I did what you said and I cannot get a accurate reading. When I do it the VM will show a couple of numbers and return to 1. Then I will move my paperclip around and it will do it again. It wont stay at a certain number. It jumps from anywhere from .7-100+

 

[BlueOvalStangGT]

I just backprobed the TP sensor, CT senssor and the IAT sensor and put the ohnomter on it. I got a good reading(.5-.8) from the TPS to the CTS and a good reading(same) from the TPS to the IAT. I still cannot get a accurate reading from my battery ground to my TPS or my CTS. Could that be where my problem is? How do I fix it if so?>

 

[BlueOvalStangGT]

Ok on the ohmeter, I get like .3-.8 for the TPS,CTS,IAT all to each other. If I do the intake to the battery ground, its good. Battery to ground by oil pressure sender is good too. Oil pressure ground to manifold it good too. But when you put the manifold to the TPS/IAT/CTS its no good(DMM reads like ~100) Same when you do the O P GRND to any of the sensors or vice versa. What does tihs tell me?

 

[BlueOvalStangGT]

bump

 

[jrichker]

I just backprobed the TP sensor, CT senssor and the IAT sensor and put the ohnomter on it. I got a good reading(.5-.8) from the TPS to the CTS and a good reading(same) from the TPS to the IAT. I still cannot get a accurate reading from my battery ground to my TPS or my CTS. Could that be where my problem is? How do I fix it if so?>

At this point I recommnend that you make a post in the 94-95 specific forum and get help on locating the computer. On the 93 and earlier models it was under the passenger side kick panel, but I don't know where it is on a 94 model. The next step is to make measurements between pin 46 on the computer and ground. If they are greater than 1.5 ohm, the computer is faulty. If they are 1.5 ohm or less, then the next step is to measure the wiring between the computer pin 46 and the affected sensors.

While you are looking/asking, check to see if there are a pair of large, round, black & white wiring connectors just behind the throttle body elbow. If there is, then they may have the broken wire/bad connection. On 93 and eariler models, they got the nickname "salt & pepper shakers" because of their shape. They are a known problem area for wiring faults in the 93 and below cars.

 

[BlueOvalStangGT]

The computer on my car is also located in the same place, Razors Edge never put it back when they tuned my car. I will try with pin 46 tommorw thanks