yo 90,
Codes
81/553 and 82/552 indicate voltage output for secondary air injection solenoid did not change when activated. Possible causes for this fault are:
• AIRB/AIRD (TAB & TAD circuit(s) shorted or open.
• Fault in solenoid or PCM.
Location pic in a 90 5.8;
"...the Yellow Vacuum Line goes from the TAD Solenoid (driver's side forward solenoid) to the TAD (Diverter) Valve located at the rear of the Intake Manifold. You have to climb up onto the engine to feel the Diverter Valve or remove the Intake Manifold..The Pink Vacuum Line goes from the TAB Solenoid (driver's side rear solenoid) to the passenger side (adjacent to the Vacuum Reservoir Can) and down to the bottom of the TAB (Bypass) Valve.."
Source: by Seattle FSB (SeattleFSB)
Disconnect both solenoid connectors. Turn ignition on. Measure voltage between VPWR terminal (RED WIRE in wiring diagram below) of wiring harness connector and battery ground for both solenoids. If either voltage reading is less than 10.5 volts, repair wiring harness open circuit, and repeat QUICK TEST. If both readings are 10.5 volts or more, go to step 9).
9)Measure Solenoid Resistance :
Turn ignition off. Leave solenoid connectors disconnected. Measure resistance of both solenoids. If either reading is not 50-100 ohms, replace solenoid assembly and repeat QUICK TEST. If both readings are 50-100 ohms, go to step 10).
10) Check Circuit Continuity :
Leave ignition off. Disconnect PCM 60-pin connector. Inspect terminals, and repair if damaged. Install EEC-IV Breakout Box
instead of Box, go to PCM connector PIN
EEC IV PCM Connector Pin Depiction Pic by Ryan M (Fireguy50)
And
Ryan's PCM Pin LEGEND
leaving PCM disconnected. Measure resistance between AIRB test pin (PCM PIN 51) and AIRB terminal at wiring harness connector. Measure resistance between AIRD PCM PIN 11) test pin and AIRD terminal at wiring harness connector. If either reading is 5 ohms or more, repair open circuit and repeat QUICK TEST. If both readings are less than 5 ohms, go to step 11).
11) Check For Short To Ground :
Leave ignition off and solenoids disconnected. Measure resistance between test pin No. 51 and test pins No. 40, 46 and 60 at breakout box. Measure resistance between test pin No. 11 and test pins No. 40, 46 and 60. If any reading is less than 10,000 ohms, repair short to ground and repeat QUICK TEST. If all readings are 10,000 ohms or more, go to step 12).
12) Check For Short To Power Circuit :
Turn ignition off. Measure resistance between test pin No. 51 and test pins No. 37 and 57 at break-out box. Measure resistance between test pin No. 11 and test pins No. 37 and 57 at breakout box. If any resistance is less than 10,000 ohms, repair short to power and repeat QUICK TEST. If code is repeated, replace PCM. If all resistances are 10,000 ohms or more, replace PCM and repeat QUICK TEST.
Wiring Diagram in a 90
Source: by SeattleFSB (Seattle FSB)
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DTC 44 (KOER); Right Thermactor Inoperative;
• Vacuum hoses leaking, blocked or kinked.
• Secondary air injection valve inoperative.
• Secondary air injection solenoid defective or blocked.
"...I had a similar issue that turned out to be the vacuum line to the Thermactor Air Bypass Valve. No CEL, just a code; 1. First check that the two vacuum lines are connected to the Vacuum Reservoir (coffee can) and the resevoir is in good repair with no leaks on the bottom. Frequently the can leaks or the vacuum lines are accidentally knocked off. Check the vacuum hose to the bottom of the Bypass Valve. Check the vacuum hose to the Diverter Valve. Check the vacuum hoses to the TAB/TAD Solenoids. Then check your TAB/TAD Solenoids. These are common easy to miss problems. Once these are ruled out all that is left is: Thermactor Air Supply Hoses. One-way Check Valves. Main TAB/TAD Valves..."
Source: by Seattle FSB (SeattleFSB)
DTC 44 (KOER); Right Thermactor Inoperative; "...indicates a Thermactor Air System leak which could be anywhere from the smog pump up front to include EGR solenoiids over on the right inside fender liner and all the way to the back of the engine which is what you see in the photos. There is also a smog tube that runs along the passenger side engine below the valve cover which runs to the back of the FI plenum up to a Air Bypass Valve (plastic) crossing over to the cross-over tube (exhaust) which is connected to that and the CAT, check valve and tube below. the Thermactor system is designed to capture spent gases and ultimatley send them down to the CAT to burn off etc.If you look closely you'll see the chek valve and CO tube is pipe threaded, use some anti-seize and don't over tighten and when putting the valve on the tube, you don't need a gasket for the CO tube ends but rather just use some bearing grease which melts and forms a nice gasket seal.....this is a tip from Steve83; gaskets burn off and go away after a while and you're back with another vacuum leak etc..."
Source: by JKossarides ("The Bronco", Jean)
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DTC 33 is triggered when the EVP sensor is not closing; so EZiest & cheapest checks are to inspect & repair/replace repair any bad vac lines. for a <$ vac line test; I pull em off and use the straw sucking test; one finger over one end
EZiest & cheapest checks are to inspect & repair/replace repair any bad vac lines
if vac lines are ok then we can go into further tests on;
EGR Valve Position (EVP) - It is on Top of the EGR Valve
- MIESK5 NOTE: EVP is used on all years except for 95 5.8L California models & all 96, they use the DPFE Sensor instead of EGR Valve Position Sensor (EVP)
http://www.broncolinks.com/index.php?index=414
EVP Connector pin-Out Diagram
by Ryan M (Fireguy50)
Testing & Operation; "...The EGR Valve Position (EVP) sensor monitors the position of the EGR valve pintle. The EVP sensor converts the mechanical movement of the pintle into an electrical voltage signal which is relayed to the PCM. The EVP sensor is a linear potentiometer in which resistance varies with the EGR valve pintle movement.Voltage is fed to the EVP by the signal return circuit. As the EGR is opened the EVP directs more voltage to the EEC and less down the voltage reference circuit. The EVP sensor provides the PCM with information on EGR flow and EGR system failures. The EVP should read between 0.24 and 0.67 volts at idle with a closed EGR valve..." read more
Source: by Ryan M (Fireguy50) at
http://oldfuelinjection.com/?p=35
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DTC 74 brake pedal Not depressed after engine ID was received in KOER
