Code reader not working 91 F150
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Cargo Master
Joined: Jul 2009
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From: Des Moines
Code reader not working 91 F150
First of all, thanks to Andrew [mikehawk] and Paul [Conanski] for all their help in getting my truck operational again. I got it put back together and running yesterday.
It's running great except for a little bit of a stumble on decel, which was one problem with it before I replaced the intake gasket. Anyway, when I got it home I went to pull the codes- I have an Equus code reader- and it wouldn't work. I changed the batteries per instruction manual and it still wouldn't work. So I tried it the old fashioned way per ffi.com and it still won't run a self test.
So I'm sure I unhooked something while I was replacing the intake gasket, I'm just not sure what. Any suggestions on what I should look for?
I want to point out that I had the battery completely unhooked [both positive and negative cables] the entire time I was replacing the gasket, so I very much doubt anything could have shorted.
It's running great except for a little bit of a stumble on decel, which was one problem with it before I replaced the intake gasket. Anyway, when I got it home I went to pull the codes- I have an Equus code reader- and it wouldn't work. I changed the batteries per instruction manual and it still wouldn't work. So I tried it the old fashioned way per ffi.com and it still won't run a self test.
So I'm sure I unhooked something while I was replacing the intake gasket, I'm just not sure what. Any suggestions on what I should look for?
I want to point out that I had the battery completely unhooked [both positive and negative cables] the entire time I was replacing the gasket, so I very much doubt anything could have shorted.
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Cargo Master
Joined: Jul 2009
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From: Des Moines
I forgot to mention that one thing I'm yet to do is pull the plugs and check to see if they're fouled. I plan to do that after I get off work tonight as the shop at work has a bench grinder w/ a wire wheel on it to make cleaning the plugs easy if they need it.
I haven't heard or felt any kind of backfire or miss in the engine either.
I haven't heard or felt any kind of backfire or miss in the engine either.
Post Fiend
Joined: Jan 2005
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For the code reader check if the cigarette lighter fuse is OK.
As for the self test way are you sure the CEL is working? Did you try hooking up a small test light or meter in the circuit?
This might keep you going untill some of the experts chime in.
As for the self test way are you sure the CEL is working? Did you try hooking up a small test light or meter in the circuit?
This might keep you going untill some of the experts chime in.
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Cargo Master
Joined: Jul 2009
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From: Des Moines
As far as I know the CEL is working. It was working before I replaced the TPS about 6 months ago, then changing the TPS was apparently the problem as it hasn't come on since then. But I don't necessarily need to see a CEL for codes to be stored.
I'm not really sure why I need to check the lighter fuse for the code reader, but I'll check anyway. It's a battery operated code reader, and it will turn on, but it won't run the test when I press the button. What I mean is that I am supposed to be able to hear relays clicking and other random sounds when the test is initiated- I'm not getting that w/ the code reader or via the FFI.com method, which is why I believe I've forgotten to hook something back up when I was putting the truck back together, because my code reader worked just fine beforehand.
Thanks for the advice- I've got a test light I will try to use but I don't think that's going to be my issue.
I'm not really sure why I need to check the lighter fuse for the code reader, but I'll check anyway. It's a battery operated code reader, and it will turn on, but it won't run the test when I press the button. What I mean is that I am supposed to be able to hear relays clicking and other random sounds when the test is initiated- I'm not getting that w/ the code reader or via the FFI.com method, which is why I believe I've forgotten to hook something back up when I was putting the truck back together, because my code reader worked just fine beforehand.
Thanks for the advice- I've got a test light I will try to use but I don't think that's going to be my issue.
Post Fiend
Joined: Jan 2005
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Did you ground the STI connector back to the neg terminal on the battery when doing the self test? This makes sure you have it properly grounded.
You need power to the code reader, usually supplied through the cigarette lighter fuse but not always.
You need power to the code reader, usually supplied through the cigarette lighter fuse but not always.
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Cargo Master
Joined: Jul 2009
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From: Des Moines
Yes I grounded the STI to the neg. bat cable. My code reader usually hooks into the STI along w/ the EEC connector, but the manual also suggests grounding the STI to the neg. bat cable if the reader won't initiate the test w/ it hooked up, which I tried and still didn't have any luck.
I also just checked every fuse in the panel- they're all good. I had to of just missed something when I was hooking up the electrical connections- I had all the connections labeled but maybe I just missed one. I will double check this and get back to you.
I also just checked every fuse in the panel- they're all good. I had to of just missed something when I was hooking up the electrical connections- I had all the connections labeled but maybe I just missed one. I will double check this and get back to you.
Post Fiend
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Cargo Master
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From: Des Moines
Well, if I did miss something, I can't figure out what it is. I double checked all the electrical connections I had to remove to replace the lower intake gasket, and they all looked good. This included-
EGR/EVP, CANP, TPS, IAC, ECT, ACT, Distributor, ignition coil, condenser, the vacuum sensors that are mounted on the same bracket as the coil/condensor... I think that's all of them. There were also 2 ground wires that I had to remove but they are both hooked up in the same places they were beforehand- I also cleaned them up to make sure they were getting a good connection. And of course the injectors.
I just don't know what I could have missed. I'm going to start looking thru my wiring diagrams and try to trace the wires leading off the EEC/STI connections, see what comes up.
Thanks for your help Lazy K- I appreciate your input.
EGR/EVP, CANP, TPS, IAC, ECT, ACT, Distributor, ignition coil, condenser, the vacuum sensors that are mounted on the same bracket as the coil/condensor... I think that's all of them. There were also 2 ground wires that I had to remove but they are both hooked up in the same places they were beforehand- I also cleaned them up to make sure they were getting a good connection. And of course the injectors.
I just don't know what I could have missed. I'm going to start looking thru my wiring diagrams and try to trace the wires leading off the EEC/STI connections, see what comes up.
Thanks for your help Lazy K- I appreciate your input.
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From: Easton,Ks
For the code reader to work:
Manual transmission computers need to sense SIG-RTN on pin 30 when in neutral.
Automatic transmission computers need to sense Ground on pin 30 when in neutral.
Electronicly controled automatic computers need an operational Manual Lever Position Sensor (MLPS).
Also read:
Ford Fuel Injection No Codes?
/
Manual transmission computers need to sense SIG-RTN on pin 30 when in neutral.
Automatic transmission computers need to sense Ground on pin 30 when in neutral.
Electronicly controled automatic computers need an operational Manual Lever Position Sensor (MLPS).
Also read:
Ford Fuel Injection No Codes?
/
Thread Starter
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Cargo Master
Joined: Jul 2009
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From: Des Moines
Thanks for the input guys. I will give it a look after my truck has time to cool down as I just got home from work.
I checked the plugs and they all looked like normal wear and tear plugs- just a light tan to them- none oil or gas fouled.
I checked the plugs and they all looked like normal wear and tear plugs- just a light tan to them- none oil or gas fouled.
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Cargo Master
Joined: Jul 2009
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From: Des Moines
Okay, so here's what I found out-
There is continuity between Sig-Rtn and the EEC. However, I did not get a continuity reading between STI and the EEC. Unless I was reading the wrong chart on FFI.com, I'd like to confirm that Sig-Rtn is pin #46 and STI is pin #48 on the EEC connector. So if I'm right, I don't have continuity between STI and the EEC. What's next?
Subford I was going to check ground on pin #30, but having just gotten off work and been up for the better part of 20 hours, I had a complete brainfart and for the life of me cannot remember how to check ground. Stupid, I know, but my brain just isn't working right now. So I will check that later.
There is continuity between Sig-Rtn and the EEC. However, I did not get a continuity reading between STI and the EEC. Unless I was reading the wrong chart on FFI.com, I'd like to confirm that Sig-Rtn is pin #46 and STI is pin #48 on the EEC connector. So if I'm right, I don't have continuity between STI and the EEC. What's next?
Subford I was going to check ground on pin #30, but having just gotten off work and been up for the better part of 20 hours, I had a complete brainfart and for the life of me cannot remember how to check ground. Stupid, I know, but my brain just isn't working right now. So I will check that later.
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Cargo Master
Joined: Jul 2009
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From: Des Moines
Thanks for the confirmation subford.
After a quick nap my brain started working again, so I checked ground on pin #30- it's not grounding.
So now I don't have continuity between STI and the EEC, and no ground on pin #30. I had to put the beast back together to take to work tonight, but I started it up after hooking back up the computer just to make sure I got a good connection, and I could hear a vacuum leak. The short piece of hose that connects the PCV valve to the upper manifold is sucking air- there's just the smallest of cracks in it. So I'll get that replaced ASAP and see what difference that makes.
As for the electrical connections, what's my next step?
Thanks again- I really appreciate the help.
After a quick nap my brain started working again, so I checked ground on pin #30- it's not grounding.
So now I don't have continuity between STI and the EEC, and no ground on pin #30. I had to put the beast back together to take to work tonight, but I started it up after hooking back up the computer just to make sure I got a good connection, and I could hear a vacuum leak. The short piece of hose that connects the PCV valve to the upper manifold is sucking air- there's just the smallest of cracks in it. So I'll get that replaced ASAP and see what difference that makes.
As for the electrical connections, what's my next step?
Thanks again- I really appreciate the help.