350350

I have a variety of things going on with my '97 LT1 Camaro SS.

For the record I'm going to list everything that's malfunctioning even though some of them seem to me to be unrelated.

All of these things happened within a week of the car running fine.

1) MIL not functioning. I'm assuming this is just a bulb, but have not confirmed it yet.
2) Engine Coolant Sensor light comes on and goes off randomly. Coolant system is full, no leaks.
3) Codes 100 (MAF Circuit) 400 (EGR Circuit) and 1657 (Skip Shift Circuit) all present.
4) Underhood 'Engine Sensor' 20A fuse blows when engine is running.

Note that 2 above has been intermittent for a couple of months, but 1-3-4 happened overnight. I parked the car in the garage after a good-running joyride, and the next morning when I fired it up it ran awful, is low on power, codes present, and blowing fuse.

Here's what I've done, with little or no results:

*Watched some ****.
*Ate 3 Caramel Brownies.
*Disconnected MAF, replaced Engine Sensor fuse, tried again, blew the fuse.
*Left MAF disconnected from above, also disconnected EGR solenoid, replaced fuse, started engine again, blew fuse again.
*Cursed.
*Sat in car in garage and made car noises, listening to the radio with the t-tops out.
*Read through service manuals to catch up on the MAF and EGR wiring and operations, as well as the wiring diagrams for the Engine Sensor fuse.
*Checked for obvious damage to underhood wiring, wondering if I hit something on my joyride that could have damaged wiring and created a short. Nothing obviously damaged.

If I understand correctly, disconnecting the MAF should put the PCM into a sort of 'dumb mode' that estimates MAF-like values and it should at least run decent. It doesn't.

I know I have a lot more troubleshooting to do, but I thought I'd post to see if this combination of things jumps out as something someone else has seen, or has any advice on...

I'll retry the **** and brownies and see if that helps.

hotrod18_69

I think you should watch some more ****.. Give me 3 caramel brownies.
Then give me a mod list if any that you have done to the car..

powerslide350

I your MAF deescreened? Maybe try cleaning it with some electric contact cleaner(non residue)

You just need to replace the low coolant sensor, it bad and is a common problem.

Injuneer

Coolant LEVEL sensor is a common problem. Gets crudded up and fails. Try cleaning it. Does not affect PCM, since it doesn't connect to the PCM.

97's seem to have a problem with the pink wire that supplies +12V to the MAF sensor. In between **** videos, check the pink wire in the MAF sensor connector for +12v, referenced to the black/white ground wire.

P0400 sets when the PCM cycles the EGR valve and the MAP sensor reading does not change like it should when the EGR valve operates. Could be due to low back pressure in the exhaust, or a problem with the vacuum lines, faulty valve, plugged exhaust gas passages in the manifold. The code is not for the solenoid circuit. P0403 is for that.

Look in your Owner's Manual and check the list of what is on each fuse. Check each of the items listed for the fuse that is blowing.

Watch more ****.

350350

I knew **** wouldn't fail me!!!

:thinking: I dunno. Granny Judy bakes them from scratch... but I guess if you can make my car run again... [Holds out 3 caramel brownies... don't tell Heather!]

D'oh! I haven't posted for a while... mods are brief but possibly important here...

*4.10 gears.
*Skip Shift eliminator.
*Loudmouth Catback.
*Hypertech Powerprogrammer Plus PCM tune plus calibrations for tires and above gears.

You know, now that I think about it, I did take apart the ductwork around the hood scoop, down to the MAF, inspect the MAF, and put it back together. I didn't think it was worth mentioning because the filter is clean and the ductwork all looks good (no vacuum leaks, etc.) but I don't recall the MAF having a screen. I'll have to check this out tomorrow. I didn't descreen it myself, but it may have been that way from the previous owner... ???

350350

How so? I'll check the voltage as you described, but when you say '97's had a problem, is it in the wiring itself, or what specifically should I look for if it doesn't show 12v?

If I must. I really shouldn't mix tech posts and **** though. I was reading through the manual thinking, "Where the hail is the diagram for the MILF Sensor???"

350350

I have the GM Service Manuals for my car (quoting GMP/97-F-2 below FWIW) and page 8A-11-3 gives a table listing the following for 'Engine Sensor' fuse (fuse 10):

*Heated O2 Sensors (2 manifold, 2 cat).
*MAF Sensor.
*Reverse Lockout Solenoid.
*Skip Shift Solenoid.

Note for the record that the Skip Shift is disabled via eliminator, but as I see it, any of the above could/would blow the fuse and therefore cripple all of the other circuits. That seems like it was planned badly: The skip shift solenoid can blow the same fuse that powers the MAF???

So anyway, I'll check underneath for shorts in the trans and cat wiring... But thought it was noteworthy that I'm getting codes for both the skip shift and MAF and they're wired together at some point.

Injuneer

The pink wire that supplies power to the MAF breaks somewhere in the wiring harness. I don't think anyone has pinned down exactly where it happens, but its not an unusual problem on the 97's, for some odd reason. Generally not a problem on other years. The "fix" is usually to run a new wire.

Yes, anything on the list can blow the fuse - that's why I recommended you check the list. Maybe the skip shift eliminator shorted. Maybe while you were driving it aggressively an O2 wire burned against the exhaust.

The code for the skip shift is set because the PCM checks the voltage on the circuit, and there isn't any when the fuse is blown. Surprised you aren't getting one for the reverse lockout solenoid as well, since that is voltage dependant. The MAF codes sets when the reading does not change over a period of time. It won't change without a power supply. The codes for the O2 sensor heaters are set based on the time required for the sensors to heat up enough to become active, so they won't set the code until the engine has been running a while.

94zgreenmachine

Here is a tip also. Don't eat Cheetos and watch **** at the same time. Your ***** will be orange.

woodysz28camaro

I have the same problem on my '96 camaro. I've tried putting a 30A fuse in it and still pops it. It seems like when I replace the fuse I get one good run and then after I stop and go again it pops. I thought it maybe could be something with the brakes seeing it blows the fuse when I stop I've changed the brake switch under the dash but that didn't help. I have had the computer scrubbed by fast chips so there is no O2 sensors, no EGR, my MAF is set for speed density mode so the reading is always the same. When I got the PCM programed it ran awesome for 2 years and now all the sudden it runs like a mustang. So if anybody else has ANY more ideas please let me know. I'm gonna make some brownies and watch some **** myself then check this little pink wire.

Injuneer

You mean you also have the 20A "Engine Sensor" fuse in the underhood box blowing? But you replaced it with a 30A fuse (not a good idea) and it is still blowing?

Did you look in your Owner's Manual to see what loads are on the fuse?

Did you check each of those services for a short?

You say you have no O2 sensors at all.... including the pre-cat sensors? You are running an open-loop tune? That would rule out the heater circuits for the O2 sensors.

Its programmed in speed-density, so I assume you don't have the MAF installed. He had to have programmed out all the codes for the MAF, so its not likely the pink wire in the MAF sensor connector is affecting anything.

Is your can an A4 or an M6 - that will affect what loads are on the "engine sensor" fuse?

rich152

Injuneer you have some good insight. I would look just like he said 3 posts up. I would be willing to bet you burned a wire on the o2 sensor or the connection itself. The o2 will still work but but the o2 heater wont. Its probably shorting to your exhaust.

350350

I have diagrams for '97, I would assume similarity for '96 but have no way to verify it. I can scan/post them if nobody will coronary over copyright stuff.

As noted above by Injuneer the diagrams are different for A4/M6.

woodysz28camaro

I did check the owner's manual and here is what it shows on that fuse, MAF sensor, Heated oxygen sensor, Reverse lockout solenoid, Skip shift solenoid, automatic transmission, & brake switch. I have an automatic so it would elminate the "skip shift" part of the fuse but still leaves the "automatic transmission" part open. I still have my MAF installed just because I don't have anything to fill the void there I've unpluged it and it still blows the fuse. I don't have any O2 sensors at all but I have the connectors still under the car but nothing plugged into them, I happened to have an O2 simulator lying around so I plugged that in to keep dirt and crap out of it. I changed the brake switch, the speed sensor on the side of the tranny and my fuel filter just to rule out a plugged filter. I ran it around and the fuse didn't blow but it still ran like crap. The longer I ran it the better it got and still didn't blow the fuse. I won't have time to tinker with it today but I'll let everybody know what happens the next time I take it out. I also bought some electrical spray and sprayed as many connectors as I could find and sprayed the whole fuse box (the one under the hood) so maybe that helped.

Injuneer

Do you have +12V on the pink wire, when measured to the black/white wire in the connector? Maybe the wiring is shorted somewhere in the harness. The 97's have a problem with the pink wire, but not as often on the 96's.



Moderator Input:

You might want to start a new thread of your own. As you can see, tacking your problem onto someone else's thread is causing confusion. That's generally called "highjacking" and not a good thing to do.