Check engine light obd1 dtcs

thcscubajohn · Aug 15, 2016

Hello everyone I'm having trouble with my 1994 ranger 4.0 manual. the check engine light would come on when driving uphill in overdrive so I wasn't too worried about it then I changed my valve cover gaskets and I broke 2 vacuum lines after that the check engine light would come on right away I still was not worried because registration wasn't due for another 9 months and it didn't effect driveability now registration is coming up and I can't pass smog with the check engine light on so I fixed the vacuum lines and then I checked the dtcs and have the following

99- ISC needs to learn idle 2 mins, clear, retest
81- AIRD/boost control solenoid
57- intermittent neutral press switch circuit
55- no or low power to pcm pin 5
56- MAF sensor high
65- check intermittent HO2S signal or ground

My battery terminals were making bad contact so I took them off cleaned them put those stupid pads underneath put them back on and covered them in grease (I didn't have any anti corrosion spray) I thought that most of these codes were stemming from the terminals and after I took them off and put them back on the codes would clear but after I did this the check engine light came back on in less than a minute after starting the engine I haven't checked the codes again but I figure that they are the same and I would also like to know if i am supposed to clear them another way besides disconnecting the battery also sometimes after its in gear and I'm driving I'll push the clutch or put it in neutral and the idle won't catch and it will stall I believe this is the idle air control but maybe not

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RonD · Aug 16, 2016

1994 Ranger Computer will use 3 digit codes which is why the 2 digit codes don't make sense, so.........................you will need to get them again.
Or if you still have the correct order written down then break them into 3 digit codes.

I believe all the 4.0l Rangers were 3 digit OBD until 1995 when OBDII(4-digit) was used, but 1994 Ranger for sure uses 3 digit.

3 digit Code list here: http://www.therangerstation.com/tech_library/3digitcodes.shtml

Video here with 3 digit code retrieval using CEL(check engine light): https://www.youtube.com/watch?v=X07hu0kAuzE

thcscubajohn · Aug 16, 2016

RonD said:
1994 Ranger Computer will use 3 digit codes which is why the 2 digit codes don't make sense, so.........................you will need to get them again.
Or if you still have the correct order written down then break them into 3 digit codes.

I believe all the 4.0l Rangers were 3 digit OBD until 1995 when OBDII(4-digit) was used, but 1994 Ranger for sure uses 3 digit.

3 digit Code list here: http://www.therangerstation.com/tech_library/3digitcodes.shtml

Video here with 3 digit code retrieval using CEL(check engine light): https://www.youtube.com/watch?v=X07hu0kAuzE

Okay thank you this makes much more sense the revised dtcs are:
565-Canister Purge 1 solenoid/circuit failure
998- Did not pass Key On Engine Off test yet (Get 111 in KOEO first)
157-Mass Air Flow signal is/was low or grounded
This makes much more sense because when I first got the truck there was a problem with the vacuum line to the canister that I patched so it would pass smog 2 yrs ago and I knew that my MAF was probably bad so I'll fix the line to the canister and get a new MAF also do you think that a good cleaning to the MAF will remove the 157?

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thcscubajohn · Aug 16, 2016

And how do you clear the codes properly without an obd1 reader

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RonD · Aug 16, 2016

You can either unhook battery for 5 minutes or after you have the codes, turn off the key then turn it on again and start reading the codes one more time, but before the codes are finished being displayed pull out the Jumper wire on the OBD test port, that will reset computer.

Cleaning MAF won't hurt but I would check the 4 wires and connector as well.
MAF sensor operates at fairly low voltage, .3volts to 3.5volts, lowest voltage at idle, lowest air flow, so even a little corrosion can cause low or 0volt(ground)

565 could be a wiring problem or bad solenoid, on the vacuum line to the canister you will find the solenoid, it is a valve the computer opens and closes by powering it and cutting power.
You can test it by unplugging its connector and using 12volts and Ground from battery, you should hear an audible "click" when it has 12v and a ground, there is no polarity, so there is no 12v pin/side, as long as it has 12v on 1 pin and ground on the other it should "click"

If it does "click" then start tracing the wires, especially near exhaust pipes.

If it doesn't click you can pick these up at wrecking yards, take a 9volt battery with you, it has enough power to activate this type of solenoid, so you can test it before buying it

Not sure the 565 code will clear, it is an emissions code and they often won't clear until problem has been solved and truck has been thru 3 or 4 drive cycles
1 Drive cycle is a full warm up and cool down

thcscubajohn · Aug 17, 2016

RonD said:
You can either unhook battery for 5 minutes or after you have the codes, turn off the key then turn it on again and start reading the codes one more time, but before the codes are finished being displayed pull out the Jumper wire on the OBD test port, that will reset computer.

Cleaning MAF won't hurt but I would check the 4 wires and connector as well.
MAF sensor operates at fairly low voltage, .3volts to 3.5volts, lowest voltage at idle, lowest air flow, so even a little corrosion can cause low or 0volt(ground)

565 could be a wiring problem or bad solenoid, on the vacuum line to the canister you will find the solenoid, it is a valve the computer opens and closes by powering it and cutting power.
You can test it by unplugging its connector and using 12volts and Ground from battery, you should hear an audible "click" when it has 12v and a ground, there is no polarity, so there is no 12v pin/side, as long as it has 12v on 1 pin and ground on the other it should "click"

If it does "click" then start tracing the wires, especially near exhaust pipes.

If it doesn't click you can pick these up at wrecking yards, take a 9volt battery with you, it has enough power to activate this type of solenoid, so you can test it before buying it

Not sure the 565 code will clear, it is an emissions code and they often won't clear until problem has been solved and truck has been thru 3 or 4 drive cycles
1 Drive cycle is a full warm up and cool down

Okay the MAF was dirty and the solenoid was unplugged I cleaned the MAF really well and plugged in the solenoid not sure if it works I'm going to try that 9v battery trick today but first I've got to clean the terminals really well first because I hate cleaned them then put them back on and I didn't have any anti corrosion stuff so I covered them in hi temp bering grease and with all the taking off and putting back on to try and clear the codes it got in between and now the truck won't start so I've got to clean those

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thcscubajohn · Aug 17, 2016

And I'll check all the wires

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Check engine light obd1 dtcs

thcscubajohn

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