At wits end and could really use some help. Codes P0689, P1516, P1682, P2101

Hey all! Tuning a newly-swapped 402 in my 2006 TBSS (E40 & A4). As of a couple days ago I started getting the following codes after every write:

P0689
P1516
P1682
P2101

Throttle body stops responding and motor will crank but not fire. Odd thing is after 15min or so of just sitting there (and a couple of disconnecting battery cycles) the problem stops and motor fires right up. But as soon as I make a tweak to the calib (like simply changing the Base Running Fuel Air a little) and then write the tune, the codes come back and I have to wait it out again. The last month or so (not including the last few days) I could simply stop, make a tweak to the calib, upload, then take off again.

I've searched _all_ over the interwebs and this forum for a solution, playing with the 1516 and 2101 % settings in Engine Diag/Airflow, and I can't seem to fix the issue. It's not the throttle body (I swapped out with a known good one and didn't fix the problem), not relay, fuse, or electrical related. It only happens after I do a Write.

Has anyone had the same problem or know of a fix? Yesterday I was at a stoplight and the motor just shut down in the middle of traffic. 15min later (after frantically trying to figure out WTH happened) the motor fired back up.

Thanks everyone!

Jesse

Check G108, drivers side of the block. Put a wrench on it, don't just look at it and say "looks good from here!" Make sure the wires aren't broken at the crimp.

Oh, and replace the ignition switch. ACDelco, no store brand knockoffs.

Ding Ding! Blindsquirrel I think you got it.

A little more trial and error and I think I figured out what was happening. The ignition switch (when turning on) has 3 detents. What I thought was ACC, and then ON, then START. I found that I could upload a tune to the ECU by only turning it to ACC (lights up the battery idiot light only). The problem seems to be that this switch does NOT have an ACC position. See, whenever I uploaded a calib the ECU would do some sort of systems test on the throttle body (it jerks it a little), most likely to verify that it's there, responds to motor input, and outputs data on the TPS.

But when I did an upload using the "ACC" position it wouldn't run this TB test. So now I upload by rotating the igntion switch to the proper ON position and am no longer having problems. Time to replace the ignition switch.

Yeah, ignition switch replacement on these trucks should really be in the maintenance schedule like oil changes and oxygen sensors. 'Every 3 years or 60,000 miles, whichever comes first...'

I keep a new spare in the glove box along with a set of tools to change it on the side of the road, just in case.

I spoke too soon. It's not the ignition switch, or the throttle body. (Both are brand new).

After installing both the truck was running fine. I couldn't duplicate the issue so I thought it was fixed. Until I went out to dinner....and got stuck....and took a tow truck ride home.

When I got it home and charged up the battery it fired right back up again. I measured the voltage on Fuse 16 (TBC) and it was 12v so all fine. For shits and giggles I turned on the A/C and let it idle for awhile. After about 15mins I goosed the throttle a little and then it shut down. Kicked out the following codes:

P0443 (Evaporative Emission Control System Purge Control Valve Circuit Malfunction)
P0689 (ECM/PCM Power Relay Sense Circuit Low)
P1516 (Throttle Actuator Control Module Throttle Actuator Position Performance)
P1682 (Ignition 1 Switch Circuit 2)
P2101 (Throttle Actuator A Control Motor Circuit Range Performance)

The only thing left to do is pull the front fuse box apart and examine for issues. Suggestions?

Thanks!

I still say G108 should be checked. I've seen it cause weird intermittent glitches just like this and your mention that it started after an engine change is a great big red flag.

If you don't find anything there, then yeah, you get to drill out the plastic welds and play with the 3d puzzle that is the front PDC.

I checked G108 last night. Loosened it, then tightened back down. I'm going to check over all the grounds tomorrow when I can crawl though the engine compartment without 3rd deg burns lol.

Edit: This is what I'm going to check in the fuse box. With all the shaking this new motor does now (lope) I wouldn't doubt this is the issue I'm having. The symptoms seem to match (as well as the codes).

https://www.youtube.com/watch?v=Rogn4SNh40o

It was the fuse box. Little copper wire was broken and expanding (breaking contact) due to engine bay heat. Soldered it back together and added a bypass as well in case issue comes back. Cant make it shut down now so.looks like it's fixed.

Quote:

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Originally Posted by jdn181

It was the fuse box. Little copper wire was broken and expanding (breaking contact) due to engine bay heat. Soldered it back together and added a bypass as well in case issue comes back. Cant make it shut down now so.looks like it's fixed.

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Still fixed?