P1682, P0689, P2176 codes and no start when warm

C-ya

Original poster
Member
Aug 24, 2012
1,098
Well, the fuse block bug bit me this week. Drive to work Monday, Tuesday, and Wednesday mornings, temps in the 20s, drive home for lunch, temps in the 40s. Truck won't start to drive back to work. Cranks over strong, spins fast, no combustion. Fired right up when I got home from work, temps in 40s-50s. No codes on Monday, but Tuesday I had P1682. Wednesday, I hooked the Tech II up and got the other codes, including P0443 (saw someone else got this one with the three I list in the title).

YouTube searches of the fault codes brought up some great videos. One of those videos lists this PDF as a source of info - Link. Really handy to see in picture form. The break was right where the 'net said it would be. I raised the wire up for the picture, but it wasn't visible to the naked eye. Meter showed no continuity.

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I'll get it back in the truck this afternoon. I expect no further trouble from it. Famous last words, I know...
 

C-ya

Original poster
Member
Aug 24, 2012
1,098
I'm going to resurrect my old thread. I have had intermittent starting the last few weeks. Codes are P0689 (ECM/PCM Power Relay Sense Circuit Low), P1682 (Ignition 1 Switch Circuit 2), P2176 (Throttle Actuator Control System - Idle Position Not Learned), and B2AAA (Scanner Communication Incompatibility).

I'm going to get back into it and chase the grounds down and check them. Any other thoughts on where to go? I replaced the ignition switch earlier before I found the broken wire. Should I dive back into the fuse block? The mechanic seems to think that is the culprit.
 

C-ya

Original poster
Member
Aug 24, 2012
1,098
Well, just for giggles, I swapped the Powertrain and Starter relays (60 & 47) and it started right up. I'll try wiggling 60 if it does it again and see if it starts. If so, I'll order a fuse block.

ETA: Just went to try again and it started and died. Wouldn't start back up. Wiggled the relay, swapped it, but didn't paperclip it. I think I'll order a fuse block. If $200 fixes it, I'll be happy.
 
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Mooseman

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Dec 4, 2011
25,257
Ottawa, ON
It sure looks like a power or ground problem. Have you tried replacing the ignition switch?
 

C-ya

Original poster
Member
Aug 24, 2012
1,098
I haven't tried it this time. I have the old one, so I may put it back in since that wasn't the issue last year. The current one is AC Delco, so I would hope similar life to the original - if it indeed was the original.

I ordered the fuse block but it won't be here until after the 22nd. I have a paperclip in the vehicle now though, just in case.
 

C-ya

Original poster
Member
Aug 24, 2012
1,098
Fuse block arrived yesterday morning so I got it in yesterday evening. Very quick shipping given the expected arrival date. Started right up and again this morning. The paperclip had caused a new code - P0690, but it started up every time.

One question I have is this - it came populated, but some of the relays were rotated the opposite way of the block I took out. I turned them the way the "old" ones were. How do we know what is the correct orientation for the relays? They are not keyed, poke yoked, or marked in any way. Well, the two relays I was swapping (60 & 47) are marked, but the block isn't. I guess if you put it in the wrong way the coil would burn out rather quickly and then that function wouldn't work.

It also looks like some of the relays have been superseded with new part numbers. No big surprise, I guess.
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
4 pin relays can be put in either direction. Those that have just one way are made to go in just one way. I think the fan and headlight relays (actually PWM modules) are like that.

As for P0690, we don't have much info on it here. This site has some info:

Possible Causes are listed as Defective PCM power relay, Blown fuse or fusible link, Open or shorted circuit between the power relay and the PCM.

Try disconnecting the battery for 30 minutes to reset everything and check/replace the related fuses and relays. Maybe check that the PCM is receiving proper voltages and grounds.
 

C-ya

Original poster
Member
Aug 24, 2012
1,098
Thanks for the info on the relay orientation. I figured it had to be fool-proof, but I knew if there was a fool big enough to find out, it would be me!

I have no CEL at present. The P0690 was due to the fact that a paperclip was supplying +12VDC at all times to the PCM, not just when the relay closed to give it the voltage. I knew why it was there, and now that everything is back to normal, everything seems to be back to normal. :smile:
 

C-ya

Original poster
Member
Aug 24, 2012
1,098
As Mooseman says they can go either way. And the reason is that the pairs of terminals, coil or contacts, are on diagonally opposite corners. So whichever way you put it in the socket the paired terminals are still proper.

LOL! I put the paperclip in diagonal holes but that reason never dawned on me! SMH...
 

gmcman

Member
Dec 12, 2011
4,656
@C-ya forgive me for not looking into the codes but when I read this, what's coming to mind is have you checked the current draw on the starter?

I would disconnect the battery ground, then remove both the large wires from the solenoid and take a piece of sandpaper to the contacts. I may even (carefully) energize the solenoid with those wires disconnected and measure the resistance across the large posts but that's a stretch.

Check the cable to the starter for corrosion or broken wires.

Did that piece of wire break right in the middle? If so, that's a lot of juice to break it unless it's caused by vibration or something else.

Just some ideas, but almost sounds like the starter could be drawing large amounts of current unless I'm looking at the problem incorrectly.
 

C-ya

Original poster
Member
Aug 24, 2012
1,098
Did that piece of wire break right in the middle? If so, that's a lot of juice to break it unless it's caused by vibration or something else.

Yes, the wire breaks due to hot and cold expansion and contraction, and I'm sure vibration plays into it. Well-known GM fault in cars and trucks as is the reason I replaced the block - loose socket connections. The initial fault was repaired last year. I just resurrected the thread since it was the same codes and ended up being another fuse block fault.
 

gmcman

Member
Dec 12, 2011
4,656
Not able to see your vehicle in person, I would start, or if you already have, double-check the battery cable side terminals, make sure they are clean and making good contact with the battery.

Then I would check the ground at the LF fender and I'm not sure if there's one on just the engine, or engine and trans. Then I would make sure the starter leads are clean.

You have other codes that direct away from the starter, but doesn't discount the damage that can be done by high current draw from the starter.

May not be the correct procedure, but those are bases I would absolutely cover. If that wire broke right in the middle of it's overall length, that also raises a brow to excess current....like a fused link.
 

C-ya

Original poster
Member
Aug 24, 2012
1,098
@gmcman , no faults at the moment.

The most recent troubleshooting stemmed from a crank/no start situation caused by the PCM relay not seating.
 
May 2, 2021
54
Kailua Kona HI
Currently getting crank no start also seemed when after driven. When I reset (disconnect ground for 30 minutes) it fires up and runs until I shut it off also cools down so not positive if it's reset but think so. Haven't stalled yet, does seem like it has a misfire. Throttle code was from shooting brake or carb cleaner at my buddies shop while cranking to verify spark or fuel pretty sure that's what they were doing at least. I was told it could be ignition switch, crank sensor or fuse box possibly... split fuse box (pita winging it before realizing I had to pull the bolts and drill the barrels) and didn't see anything broken also ohm'd out ok. I did post this is my mod post but figured might be better suited to the same type issue thread... codes are consistent I believe. Also my rear o2 goes when I drive enough as it's cut and I can barely wiggle under there so I unplugged it and zip tied broken wires out of the way. And I do have barrel crimp splices for map sensor as that was rat eaten when I bought this thing a week ago (was sitting at my dads place 2hrs away til Thursday) drove over Thursday the 2hr trek no problem but I also didn't turn it off and restart it. Tried checking voltage at fuse 22 compared to battery but my fluke is for higher voltage so didn't see a difference. Thinking for $40 I'll just change the damn ignition switch to rule it out today since I'll also be doing calipers horrible day yesterday 12+ hours and just seemed to get no where or worse. Calipers locked on a test drive down the hill so bad my coolant was boiling after coming back. Was scared to stop n let it cool for fear of being stuck on the side of the road 😩
anyway. Will get an iginition switch and see if it helps and will be changing front calipers and hope I didn't do any damage overheating the motor or trans 😳
 

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Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
Just a hunch, try disconnecting the fan clutch. When it goes bad, it can short out the 5v reference for most of these same circuits that it's throwing codes.
 
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May 2, 2021
54
Kailua Kona HI
I took apart my fuse box and ran a new wire for the pcm this morning with 20awg doorbell solid copper wire. Than finished my brakes cause it was in stands and I broke a piston on passenger caliper. It's also leaking atf pretty sure. Lol least I got it started a bunch of times and no p1682 took it to 100 on the highway, kinda took a while but it got there. I'm gonna replace the rusted/rotted out trans cooler and lines.

Is it ok to drive within 10 miles maybe so long I keep topping it off? If not it'll just sit but since it starts now I can get the safety and registration/plates. Currently have my tb plates and safety on it so I don't get a second look. Without plates is kinda asking for trouble. Have insurance on both of them anyway but rather not get extra attention.

Besides that, now I'm down to troubleshooting the other issues that I caused from driving it that 10 minutes til it boiled with the brakes locked half of which was uphill. Maybe some of it was pre-existing who knows. It was sitting non-running in a yard when I got it a week ago covered in mold/moss lol so it's already quite a ways better off. Thankful for finding this forum. Trailvoy and offroadtb don't seem as frequented I've lurked there since my 1st tb like 6yrs ago lol pic is of where it was last night til this am
 

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Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
Trailvoy and offroadtb don't seem as frequented I've lurked there since my 1st tb like 6yrs ago lol pic is of where it was last night til this am
Trailvoy hasn't been frequented since 2011 when the jailbreak happened. Mostly tumbleweeds and lost souls there.


As for ORTB, it's more specialized and with the demise of this platform in 2009, it has declined in popularity and availability for modding. We do reference to it occasionally for some useful info.


That's good info on repairing the fuse box copper traces using solid wire. As these trucks age, we have been getting more like this. You would think the OEM would have protected these. Was it broken from corrosion or burnt/melted?
 
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