Can't read codes on 87
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Mountain Pass
Joined: Oct 2002
Posts: 149
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From: Metro Atlanta
Can't read codes on 87
I went to extract the codes out of my 87 F150 XLT Lariat 5.0L tonite. I've actually never tried to extract codes form this vehicle before, BTW.
I shorted the single connector to neg, turned on ignition, waited for Check Engine light to flash, & nothing happened. Thinking the lamp may be burnt-out, I connected a voltmeter to the Output pin on the 6-pole connector & still nothing after turning ignition to ON. I then watched for the Check Engine light to turn on at all with switch & nothing. I then took negative cable off of battery, shorted it out to the positive cable to kill everyting in the EEC & tried it all over, & still nothing. My Clymers manual says take it to a mechanic, but I'm the only mechanic I know & trust.
Do I need a new EEC? The truck has been running sort of rough, cuts off when coming to a quick stop & poorer than normal gas milage.
Can anyone enlighten me? What can I try next? Will renting a Code reader help? And where is the EEC located? I think I found it under the dash just off to the side under the radio????
I shorted the single connector to neg, turned on ignition, waited for Check Engine light to flash, & nothing happened. Thinking the lamp may be burnt-out, I connected a voltmeter to the Output pin on the 6-pole connector & still nothing after turning ignition to ON. I then watched for the Check Engine light to turn on at all with switch & nothing. I then took negative cable off of battery, shorted it out to the positive cable to kill everyting in the EEC & tried it all over, & still nothing. My Clymers manual says take it to a mechanic, but I'm the only mechanic I know & trust.
Do I need a new EEC? The truck has been running sort of rough, cuts off when coming to a quick stop & poorer than normal gas milage.
Can anyone enlighten me? What can I try next? Will renting a Code reader help? And where is the EEC located? I think I found it under the dash just off to the side under the radio????
Lead Driver
Joined: Nov 2002
Posts: 9,557
Likes: 44
From: Concord, NC
The check engine light is not wired on '87 trucks for some reason. You need an analog volt meter to get the codes. Jumper the two pins just as before, but connect the volt meter between the positive battery post and the STO pin on the diagnostic connector. Then count the sweeps just as you would count the check engine light blinking. I've never tried, but I'm thinking a digital voltmeter on the continuity test would work probing the STO pin and ground. Then you could count the beeps. I haven't done this myself, but I don't see why it wouldn't work.
Senior User
Joined: Oct 2005
Posts: 389
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From: Berlin, CT USA
Originally Posted by EPNCSU2006
The check engine light is not wired on '87 trucks for some reason. You need an analog volt meter to get the codes. Jumper the two pins just as before, but connect the volt meter between the positive battery post and the STO pin on the diagnostic connector. Then count the sweeps just as you would count the check engine light blinking. I've never tried, but I'm thinking a digital voltmeter on the continuity test would work probing the STO pin and ground. Then you could count the beeps. I haven't done this myself, but I don't see why it wouldn't work.
Thread Starter
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Mountain Pass
Joined: Oct 2002
Posts: 149
Likes: 0
From: Metro Atlanta
I used a $500 Fluke meter that's plenty fast enuff for this, tried dc volts in manual range mode as well as continuity mode & got nothing. If there was a voltage/resistance change, I would have seen it with this meter!
Any other ideas as to why it gives no codes?
Also, if this truck is NOT connected up to the CEL, can I connect it up so it is easier to read (w/o meter) when I do get it working?
TIA,
Rick
Any other ideas as to why it gives no codes?
Also, if this truck is NOT connected up to the CEL, can I connect it up so it is easier to read (w/o meter) when I do get it working?
TIA,
Rick
Lead Driver
Joined: Nov 2002
Posts: 9,557
Likes: 44
From: Concord, NC
You can hook up the check engine light, but it will take some splicing. Basically, run a wire from the STO near the test connection up to the back of the instrument cluster. You'll likely have to move a pin from the cluster harness; I chose the one for the EMISS light because it is nothing more than a timer anyway.
Last edited by EPNCSU2006; Nov 17, 2005 at 06:16 AM.
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Mountain Pass
Joined: Oct 2002
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From: Metro Atlanta
Well,
I got the codes off the EEC. Had to thoroughly clean the connectors so they made contact with my jumpers. Since I had deleted all the codes the other day, only had a few. Here's what they are:
11 11 1 33 33
Where can I find a list of the codes?
I got the codes off the EEC. Had to thoroughly clean the connectors so they made contact with my jumpers. Since I had deleted all the codes the other day, only had a few. Here's what they are:
11 11 1 33 33
Where can I find a list of the codes?
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Mountain Pass
Joined: Oct 2002
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From: Metro Atlanta
OK - So I decided to forget the code thing & look at the sensors & actuators.
1: I found the Water temp sense physically broken but possibly functional - will replace anyway.
2: Found EGR valve stuck - sprayed PB Blaster on it & let it soak for an hour, put a 20 psi vacuum on it 7 hit it with a hammer till it released & excersised it for 10 mminutes with vacuum pump.
3: Found EGR position sensor dirty, ran in & out fast many times till ohming out with a clean reading for full range.
4: cleaned Idle spped sensor assembly - same deal with sensor as EGR sensor.
Will replace Water temp sensor tomorrow & drive it then with a clean base line in the EEC. Looking forward to a better running truck!!!
1: I found the Water temp sense physically broken but possibly functional - will replace anyway.
2: Found EGR valve stuck - sprayed PB Blaster on it & let it soak for an hour, put a 20 psi vacuum on it 7 hit it with a hammer till it released & excersised it for 10 mminutes with vacuum pump.
3: Found EGR position sensor dirty, ran in & out fast many times till ohming out with a clean reading for full range.
4: cleaned Idle spped sensor assembly - same deal with sensor as EGR sensor.
Will replace Water temp sensor tomorrow & drive it then with a clean base line in the EEC. Looking forward to a better running truck!!!