Idle issues (1 Viewer)

[Keith87VT]

So using a voltmeter I discovered a big issue... I have 0 volts reaching my emissions components. Tested at battery I have 12.7v, 6 inches away it's the same, but then the wires start to split and it's hard to follow where stuff goes so I tested the ics plug itself, the green plug on the passenger side on top of what looks to be a canister of some sort and the plugs next in line on the harness after the ics. None of them had any voltage going to them... But the headlights work as does cig lighter, and other assorted electronics. So what it seems is that all the emissions stuff is not getting juice. Is there one source spot where these wires all separate from the headlights and other electronics, and go on their own journey to pissing me off?

 

[Slow Left]

All Emissions components that ground through the Emissions Computer are behind:
1) Ignition Relay - the inductor side of this relay is behind the 'Gauge' fuse (5 Amp)
2) 'Engine' fuse (10 Amp)

Check (pull each one and visually check them and/or do a continuity (resistance) measurement to make sure they conduct) these two fuses in the fuse panel to make sure they aren't blown:
1) 'Gauge' fuse (5 Amp)
2) 'Engine' fuse (10 Amp)

Pull the Ignition Relay and follow the test procedure outlined in the 'Body Electrical' section of the 'Chassis-Body 1980 FSM' to make sure the relay is still good.

If you look on the wire diagram below (from the 'Chassis-Body 1980 FSM'), you see that the Emissions Computer receives power from the battery at pin #6.
If you remove the cover on the Emissions Computer and plug it back in, then ground the black(-) lead from your multimeter on the vehicle chassis (a bolt that goes into the chassis or frame), then, with the key in the ignition switch turned to 'On' (aka IG) (not ACC or Start), make contact with the positive (+) red lead to pin #6, you should read 12V+ on the meter...

 

[Slow Left]

So using a voltmeter I discovered a big issue... I have 0 volts reaching my emissions components. Tested at battery I have 12.7v, 6 inches away it's the same, but then the wires start to split and it's hard to follow where stuff goes so I tested the ics plug itself, the green plug on the passenger side on top of what looks to be a canister of some sort and the plugs next in line on the harness after the ics. None of them had any voltage going to them... But the headlights work as does cig lighter, and other assorted electronics. So what it seems is that all the emissions stuff is not getting juice. Is there one source spot where these wires all separate from the headlights and other electronics, and go on their own journey to pissing me off?

The headlight circuit doesn't go through the ignition switch (see wiring diagram), so they will turn on whether the ignition is on or not.

The Emissions components go through the ignition relay (see wiring diagram above), so unless the relay is on, they won't get power.
When the key is out of the ignition switch, the ignition is obviously off, so there is no power to the inductor on the ignition switch (that power comes behind the 'Gauge' fuse).
When the key is in the ignition switch and turned to IG or 'On' (but not 'Start' and also not 'ACC'), then power is sent through the 'Gauge' fuse and the inductor on the ignition relay flips the switch side of the ignition relay on (so the switch closes), allowing power to flow through the switch side of the ignition relay, through the 'Engine' fuse and gives power to the Emissions computer at pin #6.

So, you would not expect to see 12V at any of the Emissions components that run through the Emissions Computer if the ignition is off....but if you turn the key in the ignition to IG or 'On', then I would expect that you see 12V at those components.

Did you take those voltage measurements with the ignition on or off?

 

[Keith87VT]

measurements were taken with the key turned to "on" i believe... one click over where the dash light for choke and ebrake light up. we also tested with truck running and still had 0 volts.

 

[Slow Left]

measurements were taken with the key turned to "on" i believe... one click over where the dash light for choke and ebrake light up. we also tested with truck running and still had 0 volts.

Hmm...

I think the 'Vacuum Switch' that comes off the Emissions Computer in the wire diagram above is the one you tested on the charcoal canister. The 3 VSVs should be on the DS fender...

What about those two fuses and the Ignition Relay, do they test out good?

Also might be a good idea to run that test and measure pin #6 on the Emissions Computer with the IG on to see if the Emission's computer is seeing 12V+...

 

[LAMBCRUSHER]

no 12 volts at ICS connector...hmmm, check fuses again(pull 1x1 and measure continudity). also jump 12 volts to ICS and verify it's functional. if you have good fuses/wiring, then the ics should get +12 all the time with key ON and the computer thing switches the ground as it thinks it needs to idle. the green wire mod is where the green wire going to the ics on the chassis side of the harness is removed from the harness and grounded so whenever the key is on, the ics gets opened...with a quick desmog and rewire to fit it with green wire mod, you can bypass the computer completely and just run key-on power to the ICS to get it running...(said the guy who used to argue for the smog gear...)

 

[BlueCruiser84]

Check your fusible link at the battery. Even if they are intact they can be burned out inside the cloth coverings. Use a test light, or a volt meter or just a jumper on either side of the fusible link to make sure you are getting full voltage through it.

It's super easy to check and I have seen a burned fusible link cause many strange electrical issues including no charge.

 

[Keith87VT]

I am not sure what we are talking about when we say fusable link.do you happen to have a picture of what we are talking about? And also how to test it.

 

[LAMBCRUSHER]

punch fusible link into the search window and do some homework. soooo much info out there ready to read...

 

[Slow Left]

From the positive(+) battery terminal, follow the lead until you see this (see below).

The Wiring Diagram shows that there are 3 fusible links at that green connector.

To test, ground the black (-)negative lead of your voltmeter to the vehicle chassis.
Touch the red (+) lead on the battery side of the fusible link...it should read 12V+.
Touch the red (+) lead on the far side of the fusible link...it should read 12V+....if it does not, that fuse is bad.
Check all three fuses.
If one or more is bad, do a search here in the 60s section for instructions on how to repair/mod...

 

[LAMBCRUSHER]

From the positive(+) battery terminal, follow the lead until you see this (see below).

The Wiring Diagram shows that there are 3 fusible links at that green connector.

To test, ground the black (-)negative lead of your voltmeter to the vehicle chassis.
Touch the red (+) lead on the battery side of the fusible link...it should read 12V+.
Touch the red (+) lead on the far side of the fusible link...it should read 12V+....if it does not, that fuse is bad.
Check all three fuses.
If one or more is bad, do a search here in the 60s section for instructions on how to repair/mod...

View attachment 938574

View attachment 938575

enabler

 

[LAMBCRUSHER]

they learn more when they have to work to learn

 

[Slow Left]

enabler

...he's motivated to fix it and learn...so he's asking questions...once he gets familiar with the system(s) and tools (who really understands electrical anyways??), he'll realize that alot of the information he is asking us for is in the FSMs (explicit knowledge) and the real benefit of the MUD community is the tacit knowledge (the 'how' to approach the problem/fix...gained through experience)...

...and then the next step is that he will realize that he can create his own knowledge (through the scientific process...which includes trial and error), but that requires a certain amount of internalized explicit and implicit knowledge first (to lower the risk, if anything).

The challenge with learning nowadays is that there is WAYYYYY too much information out there...and trying to figure out what is important information and what is not important information wastes a lot of time. I find that going straight to the principle, explaining it upfront (none of the old time figure it out for yourself)....and then the learning is done when they have to apply the knowledge...learning through action...afterall, I can sit here and blabber all day long, but if he can't take the initiative and apply the information correctly on his end, then the problem will never get solved.

The real learning anyways is identifying the cause and effect associated with the problem and sometimes having gone through that a time or two sets you up to see it on your own the next time a new problem arises...or so one would expect...

I don't know, maybe I'm wrong, but just how I see it...for now at least...

 

[LAMBCRUSHER]

naw, you're doin the good stuff. I just like to see the kids do some digging themselves. we all have just been like " I just need someone to tell me WTF so I can fixit and git on" but we have also been like..."I spent my entire spring vacation reading archived threads on ih8mud..." I jest; carry on

 

[Slow Left]

naw, you're doin the good stuff. I just like to see the kids do some digging themselves. we all have just been like " I just need someone to tell me WTF so I can fixit and git on" but we have also been like..."I spent my entire spring vacation reading archived threads on ih8mud..." I jest; carry on

I hear you, but you gotta remember, we rode the learning curve back before there was MUD...if you didn't have someone around who knew what from where, then you were on your own. I probably couldn't add up all the time I wasted trying to figure something stupid out, where if there were MUD around, it would have been a no brainer...

But I really think that the discipline necessary with being a good problem solver (mechanic, etc.) will never change. In other words, when your standing fender side and trying to figure out what the hell is going on, the principles behind discovering the cause and effect never change...MUD or no MUD...

 

[Keith87VT]

I appreciate the help. Pictures make things way easier. I don't tend to ask a question until I have dug a little into the issue. Ie I had already done a search for fusable link both here and on google looking for an image of what I was looking for before asking, but it's my first trail rig so I am going in blind. I have read many forums on here and am building a working knowledge, but knowing the name of something and name of what it's next to (which is easy to find on forums) doesn't help if I don't know what any location landmarks look like either. As a side I did some trial and error yesterday and clipped and remounted terminals to remove some nasty copper, and also unplugged this link we are talking about. The female part of the green end looked burned on one of the ports so that may be our culprit. It seems that each of the 3 output wires runs a different set of systems. Having tried to read the diagrams and getting confused is there anyone who can confirm that what I'm guessing is a charcoal canister and the ics runs from the same output port on the fusible link?

 

[Keith87VT]

My guess from the diagrams is that all the issues are caused by this link. If alternator reg runs off port three as do other things or so it seems then port 3 may be the problem I just need confirmation I am reading right that port three labels with a w on the big full diagram runs the emissions system and alt regulator

 

[Slow Left]

The Wiring Diagram shows that there are 3 fusible links at that green connector (R, B, W). According to the wiring diagram, W is the fusible link for the Emissions computer circuit.

There are two ways you can test the fuses in the fusible links to see if they are functional.

To test while the link is connected to the battery:
Ground the black (-)negative lead of your voltmeter to the vehicle chassis.
Disconnect the plastic connector on the battery side of the fusible links
Touch the red (+) lead on each of three the leads on the battery side of the fusible link (so you are probing the leads on the battery side of the connector here)...each should read 12V+.
Reconnect the plastic connector.
Disconnect the plastic connector on the far side of the fusible links.
Touch the red (+) lead to each of the three leads on the far side of the fusible link...each should read 12V+....if one does not, that fuse is bad.
Check all three fuses.

To test with the fusible links removed from the battery:
Disconnect the fusible links at both connectors on either side of the fusible links.
Set your mulitmeter to measure resistance (Ohms) or continuity (1/Ohms).
Connect the positive (red) probe of the multimeter to one of the three contacts on one side of the links.
Connect the negative (black) probe to the corresponding contact on the other side of the link (if you can't tell which one is the one that corresponds, test all three).
If the fuse is good, you should measure on the order of tens of Ohms, meaning that there is a path for current to flow (so the fuse is not blown).
If the fuse is bad, you will measure infinity, meaning that there is no path for current to flow because the fuse is blown.

Test all three fuses (R, B and W) and report back if they are:
1) functioning properly and if so, what did you measure (in either Volts if you used the first test, or Ohms if you used the second test)
2) not function properly and what the measurement was

 

[Slow Left]

The path of the current from the Battery, through the common fusible link W, to the Emissions computer is outlined in the wiring diagram.

I'm fairly certain that the component labeled Vac switch off the Emissions computer is the switch you are testing on the Charcoal cannister.

The ICS is clearly marked on the Emissions computer.

Running the test above will tell you if the fusible link(s) are causing the absence of voltage in your readings of the Emissions Components. If the test on the fusible links reveals that they are good, then run the test to see if there is 12V at pin #6 on the Emissions computer with the ignition turned to 'On'.

 

[Slow Left]

... I just need confirmation I am reading right that port three labels with a w on the big full diagram runs the emissions system and alt regulator

Yes, you are reading the wiring diagram correctly. The alternator-regulator and the Emisisons computer-components share the same fusible link, labled 'W' on the wiring diagram...