I scanned my car and I got these two codes. It seems that they're related, since they both use the same fuse. Also, the Eng Sensor fuse keeps blowing. Any one have any idea why the fuse would blow? Is there a ground somewhere or a possible area that the wire could short? Any help would be great.

 

According to shoebox's DTC list, P0100 is Mass Air Flow (MAF) insufficient signal activity and P1657 is Skip shift/One to four upshift system control circuit. Seem pretty unrelated to me unless these two happen to be on the same circuit. I don't know, I work with OBD-I. Hopefully someone else can help on the diagnosis of those.

Just wanted to give you a start.

 

They both run on the same fuse, which is the Engine Sensor fuse. And that's the fuse that keeps on blowing. Anyone else have any ideas?

 

From what I can gather from other posts related to this, all 4 O2 sensors, MAF, reverse lockout solenoid and skip shift solenoid all work off of this circuit. A way to diagnose this is take out the fuse and test the circuit for a ground on the load side (which should be present since you are blowing fuses). Then just start unplugging the sensors one by one until you don't get a ground anymore. The last sensor unplugged before the ground is no longer present is the culprit sensor. If you have unplugged all the sensors and you still get a ground, you have a wiring problem--some wire has been burned or worn away and is touching metal, causing it to ground out. Wires that get burned off the most, causing this problem, are the O2 sensor wires near the manifolds. That would be what I would check first.

Hope that helps.

 

What's the best way to do this? Should I just use a volt meter? What kind of volts should they pull? Thanks for all your help.

 

Can't tell you what they'll pull exactly. You will actually need an ohm meter. Connect the one lead to the sensor side of the fuse (NOT the +12 V side, you may damage the meter), and then the other side to a good known ground. You should have zero ohms (short circuit). Then unplug each sensor, one by one, and recheck the resistance using the ohm meter again. Once you get something other than zero (it should be a very high value or infinite), that means that the circuit is no longer shorted to ground. That would be the sensor causing the problem. If you eliminate all the sensors, you can do a similar test if you have a meter that has a short circuit buzzer setting (when the resistance is lower than something like 100 ohms, a buzzer will sound). Hook up the meter in the same way as in the previous test. The buzzer should sound constantly. Then you can go around the car and wiggle the wiring to the sensors tested before. When you hear the buzzer go off, you have found the bad wiring.

 

You've been a great help. What's the best way to find the sensor side of the fuse? My volt meter has a protection deal on it, so I should be alright if I tap into the wrong side. Also, I know where the O2s, MAF, and Skip Shift are, but where is the reverse lockout soleniod located? The skip shift is on the driver's side, but I can't seem to find the reverse lockout plug. Thanks again.

 

To figure out which side is the +12 V side and which is the sensor side, use a volt meter. Put the red lead on one side of the fuse and put the black lead to a good known ground. If you get +12 V, then you are on the +12 V side. If you don't get any voltage, you are on the sensor side. The sensor side is the side you want to use with the ohm meter.

I am not quite sure where the reverse lockout solenoid is. I have an automatic, so manuals are not my thing. However, I did find this information on it. For the M6, it looks like the reverse lockout solenoid is on the same side of the tranny as the skip shift solenoid but at the very back. Here is a picture of the sensor and solenoid locations on the M6.

 

For reverse lockout:

http://cjcfo.fbody.com/members/injun...E/T56Conns.jpg

Each year is different, with regard to which fuse supplies which loads. On the wiring drawing for the 95's on Shoebox's site, the MAF comes off fuse #5 in the I/P. O2 heaters, Skip shift, reverse lockout, EGR solenoid and EEC solenoids off #6 U/H. 96 could be different.

There have been a lot of problems showing up on the pink wire that supplies +12V to the MAF sensor, mostly in 1997 cars, but sometimes in the 1996's. Generally the wire breaks somewhere back in the harness, and the MAF code sets because the sensor isn't getting any power. I guess its conceivable that anything that is broken could short to something else and blow the fuse.

 

Awesome, those pictures will help greatly. I'm going to take a peak at it tomorrow, and see what I can come up with. I'll also make sure that there's 12V going to the MAF with the key in the ON position. Thanks again for you help you guys.

 

Alright guys, I had a chance to check things out. I did the Ohms check and nothing seemed to pop out at me. They all seemed within reason. So, what I did was disconnect all of the plugs, and put a new fuse in. I also took my skip shift eliminator off. So, I turned the key to on, and started pluging things back in, and I checked the fuse after I plugged each in. I plugged them all in, and the fuse didn't blow. So, I started the car, and everything worked. The fuse didn't blow. I'm not sure if I fixed the problem, since I couldn't drive my car at the time(had to send the ECU out for tuning).

Anyways, what do you guys think? The fuse didn't blow right after start up like every other time. It looks like it was a bad resistor in my skip shift eliminator. I guess we'll find out when I get my ECU back from tuning.

 

I have a question regarding checking resistance...

When checking the sensors, do you put on lead (from the meter) to the sensor side of the fuse and the other to the sensor itself? Or, do you put one lead to the sensor itself and the other lead to a ground?

I'm confused on how to check. I have a bad wire somewhere.

Also, what is an acceptable resistance level? <10 Ohms?

Ryan