94 Bronco Fails emmissions

[kenkaplan]

Just failed emissions last week in my 94 Bronco. with 80k miles. Turned out to be the easy to replace and locate purging solenoid valve. But I am assuming for now, still needs to go back for the free re test tomorrow.

 

[miesk5]

Yo KEN,

WELCOME!

Is Check Engine Light ON while driving?

If so, delay re-inspect until you check for Codes.

Try a Self Test for Diagnostic Trouble Codes (DTC)s by my pal, BroncoJoe19

http://broncozone.com/topic/14269-code-reader/?&pid=74587&mode=threaded

The engine temperature must be greater than 50° F for the Key On Engine Off (KOEO) Self-Test and greater than 180° F for the Key On Engine Running (KOER) Self-Test.
Run it around to heat the engine up and shift thru all gears incl Reverse. Then turn off all accessories/lights, etc.

Make sure A/C is off and transmission is in Park (automatic) or in Neutral for a Manual & release clutch.

Do Key On Engine Off (KOEO) portion first.

And Post em here according to:
KOEO
&
KOER
 

•  

DTC 565 Pin-Point Testing & Possible Causes
From Ford;
Possible causes:
Open harness (VPWR or CANP). The canister purge solenoid dangles in its vacuum line between the Passenger side of the engine and the canister on the frame rail, its wiring could have hit the exhaust manifold.
Damaged CANP solenoid.
Shorted (power to ground) harness.
Damaged Powertrain Control Module (PCM) (LESS LIKELY!!!)
 

By RYAN again;
"... An important note we must cover now is that the EEC operates a majority of the sensors at 5-volts DC. ... the alternator and batteries are not dependable for voltage supply when it comes to sensitive electronics. The automotive electrical system ranges from 10-14 volts on an average day. Inside EEC is a voltage regulator, this steps the voltage down to a constant 5-volts. This voltage is called Reference Voltage (V-REF ). The sensors are supplied with this Reference Voltage and the sensor returns a variable amount of this to the EEC to indicate the status of the system the sensors is watching.

VPWR -Vehicle Power supply voltage (regulated 10-14 volts)

Some of the sensors need a special ground to get rid of the left over Reference Voltage that isn't sent to the EEC as a status. The EEC also provides a 5-volt ground loop for these select sensors. This special ground is called Signal Return (SIG-RTN). Lets quickly explain how this all works. The EEC sends a 5-volt Reference Voltage to a sensor; the sensor sends 1.87 (in your case MAP) volts back to the EEC as the sensor status, and the rest of the voltage (which should be 3.13-volts) down the Signal Return (SIG-RTN) ..."

Key on, engine off.
Disconnect appropriate CANP solenoid.
Measure voltage between VPWR at the CANP solenoid vehicle harness connector and battery ground.
Is the voltage greater than 10.5 volts?
Yes - GO to KD7
No - SERVICE open VPWR circuit. RECONNECT CANP solenoid. RERUN Quick Test

KD7 CHECK CANP RESISTANCE
Key off.
Disconnect CANP solenoid.
Measure CANP solenoid resistance.
Is resistance between 30 and 90 ohms?
Yes - GO to KD8
No - REPLACE CANP solenoid. RERUN Quick Test.

KD8 CHECK CONTINUITY OF CANP CIRCUIT
Key off.
Appropriate CANP solenoid disconnected. (some Fords have two)
Disconnect Powertrain Control Module (PCM). Inspect for damaged or pushed out pins, corrosion, loose wires, etc. Service as necessary.
Install breakout box (see Pin Outs below to check w/o this box), leave PCM disconnected.
Measure resistance between Test Pin  31 at the breakout box and CANP circuit at the CANP solenoid vehicle harness connector.
Is resistance less than 5.0 ohms?
Yes - GO to KD9
No - SERVICE open circuit. REMOVE breakout box. RECONNECT all components. RERUN Quick Test

KD9 CHECK CANP CIRCUIT FOR SHORT TO GROUND
Key off.
Appropriate CANP solenoid disconnected.
Breakout box installed, PCM disconnected.
Disconnect Scan Tool from Data Link Connector (if applicable).
Measure resistance between Test Pin 31 (refer to pinpoint test schematic ) and Test Pins 40, 46 and 60 at the breakout box.
Is each resistance greater than 10,000 ohms?
Yes - GO to KD10
No - SERVICE short to ground. REMOVE breakout box. RECONNECT all components. RERUN Quick Test.

KD10 CHECK CANP CIRCUIT FOR SHORT TO POWER
CANP solenoid disconnected.
Breakout box installed, PCM disconnected.
Scan Tool disconnected from Data Link connector.
Measure resistance between Test Pin 11, 15, 31 or 54 (refer to pinpoint test schematic ) and Test Pins 37 and 57 at the breakout box.
Is each resistance greater than 10,000 ohms?
Yes - REPLACE PCM. REMOVE breakout box and Scan Tool. RECONNECT all components. RERUN Quick Test.

No - SERVICE short to power. REMOVE breakout box and Scan Tool. RECONNECT all components. RERUN Quick Test.
...

Overview, Failure Symptoms & Depiction, general; "...Vent fuel vapors from the fuel tank to the charcoal canister, and control the purging of these and other vapors from the fuel tank into the intake manifold when certain engine speed and temperature conditions are attained. Above idle, the mixture becomes very rich. Stumble on acceleration, poor fuel mileage, flooded charcoal canister and catalytic converter overheat can occur. Check for ruptured diaphragms inside the valve and misrouted or damaged hoses..."
Source: by tomco-inc.com
...
if you don't have or can't find a break-out box. (E bay has em for $$$.00) you can also check the wires to the PCM directly
here are the EEC Connector Pin Outs, Bronco & Ford Truck & Van: 4.9, 460, 5.0, 5.8; by Ryan M;

http://web.archive.org/web/20131229163930/http://oldfuelinjection.com/images/eec04.gif

see his Connector Pin Legend

http://web.archive.org/web/20131029020805/http://oldfuelinjection.com/truckpinouts.html
 

Wiring Diagram in a 94; http://www.revbase.com/BBBMotor/Wd/DownloadPdf?id=4906