New ignition trouble code

[MrShorty]

For the CANP circuit, the wiring diagrams in Chilton's have proved adequate for me. If you don't have a print manual, you can get the Chilton's stuff by following the vehicle repair guide links at autozone.com.

On my '92, the CANP solenoid is hanging from the "vacuum" line that runs between the charcoal cannister and the throttle body. On your '94, the solenoid might be under the throttle body. In any case, follow the tube that goes from the charcoal cannister to the throttle body/intake, and you should find the CANP solenoid.

As noted in my notes on pulling EEC-IV codes thread, and probably in BrooklynBays thread as well, CM is cleared by interrupting the test anytime during KOEO/CM code output.

 

[stev0n]

okay... appreciate that, shorty. I'll get on it first thing in the morning. i'll let ya know how it goes. THANKS!!!!!!!!

 

[stev0n]

well, i think i figured out the problem...my CANP is gone. the plug is there..but it's gone.

Autozone wants $50 and they have to order it. well i don't even have $50 to my name after all the bills i just paid, so i guess i'm screwed for right now.

 

[stev0n]

alright. The KOEO gave me a 111 - pass, after putting the new CANP on!!!

I let it run and the CEL came on again. KOEO is still 111 but KOER is 998 & 157.

so MAF voltage is too low & something with the computer. What do I need to do about these?

 

[MrShorty]

There's a fault in the MAF circuit that is causing the computer to run in failure management effects mode (FMEM). I've seen this combination of codes come up here a couple of times, and it seems to usually point to a failure in the MAF. Check the wiring to the MAF, just in case.

 

[stev0n]

Okay, I bought the craftsman multimeter for $10 from sears today don't really know how to use it well..yet. I checked the MAF plug with KOEO on dc20v and here are the readings.

[————] «- MAF plug
1 2 3 4
_________________

1=0.00
2=0.02-3
3=5.66
4=0.01
__________________
I don't know what these readings are supposed to be, but there they are. So i'm not sure if they're low or which ones are low, or how to fix it.

BTW, i went to advance auto and told them the problem. The manager messed with my truck for a second and came back and said, "yep, it's gettin power. but that's all i know. if you need more in detail help you'll have to go to a mechanic." idiot.

 

[stev0n]

I also unplugged the MAF and it ran at 1500rpms for about 1 minute then died.

 

[btexpress]

messed with my truck for a second and came back and said, "yep, it's gettin power. but that's all i know. if you need more in detail help you'll have to go to a mechanic." idiot.

So what makes him an idiot? He sells parts, he doesn't fix cars. Anyone going to a parts store for diagnosis is just asking to spend needless money in the first place. If you want to know how to diagnose and fix your own problems, get some training, buy a manual.

 

[MrShorty]

The red wire going to the MAF is the "excitation" voltage for the sensor, and should be about the same as battery voltage. Since I don't see a +12V reading there, I would say something is wrong. At this point, I'm not sure if it's a fault in the wiring or an error in the testing.

What were you referencing those voltages to?

 

[stev0n]

So what makes him an idiot? He sells parts, he doesn't fix cars. Anyone going to a parts store for diagnosis is just asking to spend needless money in the first place. If you want to know how to diagnose and fix your own problems, get some training, buy a manual.

You didn't pay attention to what i wrote........I TOLD HIM I NEEDED THE VOLTAGE CHECKED - INSTEAD OF TELLING ME THE VOLTAGES WERE HE TOLD ME "HIS QUOTE".

The red wire going to the MAF is the "excitation" voltage for the sensor, and should be about the same as battery voltage. Since I don't see a +12V reading there, I would say something is wrong. At this point, I'm not sure if it's a fault in the wiring or an error in the testing.

What were you referencing those voltages to?

The voltages were from the MAF plug from left to right. I didn't have the truck running just left the key on. and I didn't know which knob to switch it on, so i set it on DC current on '20V'.

 

[MrShorty]

Sorry, I guess I didn't explain myself very well.

Voltage is not an absolute value. It's always expressed relative to something else. What I'm asking was, where was the black (negative) meter lead when those readings were taken?

Your last post said the meter was set to DC current at 20V. Not certain exactly what you mean, or if it was a typo, but make sure the meter is set to measure DC volts and not DC current (measured in Amps).

 

[stev0n]

sorry, I had it set to measure DC VOLTS not current. and I had the ground lead grounded to the negative on the battery the entire time.

Here's a Revised Diagram from the KOEO Voltage test I took this morning:

[————] «- MAF plug
[ 1 2 3 4] «- Each port numbered
_________
And the corresponding numbers:

1=red wire=11.91
2=black wire=0.01
3=blueish/pinkish wire(faded)=5.66
4=0.00

 

[MrShorty]

I didn't have a lot of time this morning before work. But here's what I can report. Just to note, my wiring diagram and my MAF connector label the connections as A, B, C, and D rather than 1,2,3,4. I'll assume they correspond. I only checked D to ground, which my manual tells me is the MAF signal wire. KOEO I got ~.2 V. Driving I got between 0.2 and 0.5 V, depending on engine speed and load.

So, back to your readings:

1=red=11.91 V -- MAF power supply this looks normal
2=black=0 V -- MAF ground, this looks normal
3=blue=5.66 V -- MAF return. ??, but I don't know that that looks right to me.
4=tan=0 V -- MAF signal. Looks way off.

something doesn't look right in the signal wire. I would verify that you had good contact between the meter leads and the signal wire/ground. Where did you take those measurements: at the MAF connector?

 

[stev0n]

i took those measurements at the plug that actually plugs into the MAF.

I just tried one more time to make sure and:
plug C was 5.66 again and
plug D was .03

I guess i need to trace this 'D' wire...that's gonna be fun as i have no idea where it goes. any advice?

 

[MrShorty]

On my '92: C and D go to pins 14 and 15 at the PCM (C goes to 14 and D goes to 15, though I may have those backwards right now). Wiring diagrams I have suggest that they could also be going to pins 50-something in some applications.

The next thing I would do would be to backprobe the appropriate pins at the PCM (careful, you don't want to damage anything or short anything out) and see if you get the same readings there. Then disconnect the MAF connector and the PCM 60 pin connector and measure continuity between the MAF and the PCM connectors as well as checking for shorts to power and ground.

 

[stev0n]

alright does the pcm have the pins numbered or how do i know which ones are 14 and 15 to check?

 

[MrShorty]

They are sort of labeled. On mine, looking on the broad side of the connector, there's a 41 at one end and a 60 at the other and I count pins on that side to find the one I'm looking for. On the opposite side there's a 1 and a 20. The middle row is pins 21 through 40.

 

[btexpress]

sorry, I had it set to measure DC VOLTS not current. and I had the ground lead grounded to the negative on the battery the entire time.

Here's a Revised Diagram from the KOEO Voltage test I took this morning:

[————] «- MAF plug
[ 1 2 3 4] «- Each port numbered
_________
And the corresponding numbers:

1=red wire=11.91
2=black wire=0.01
3=blueish/pinkish wire(faded)=5.66
4=0.00

1 is battery voltage to the MAF
2 is MAF ground
3 is reference voltage (5.0V) 5.66 is a little high but acceptable
4 is the MAF signal, with the sensor disconnected or the engine off this should be 0. With the engine running it will read between .5V and about 4.0V
depending on engine rpm (and the sensor connected!).

 

[stev0n]

the pcm plug didn't have the pins numbered so i found the signal wire (light blue w/ red stripe) traced where it went into the pcm plug and tested it. (it was, with the plug plugged into the computer, in the row closest to the driver's side and it was right next to the bolt that holds the plug into the computer.)

It showed 0.01 V

I didn't know if i needed to check the pin on the computer or the plug so i checked the plug.

 

[stev0n]

ttt