I have a 2015 Viper LTX MCI turbo fails to start

[Bluebullet]

I have a 2015 Viper LTX that has been brought to me to see if I can find the issue. Sled cranks fine, fuel pump comes on and pressurizes and shuts off. codes active are: P1689 (rev ckt low), P1692 ( fwd ckt low), P0562 (sys volt low) also the R is showing on the dash and backup buzzer alarming. I replaced the battery with and new one as the negative post was broken off. ( obvious issue) I have checked all the fuses and removed and reinstalled all the relays. ( no obvious corrosion). I cleaned and reinstalled the two ground wires above the primary clutch. This sled also has the MPI turbo modification. Lots of loose wiring job not tied down, looks like a 12 year old wired! The ECU was updated flashed by a dealer last year. Ran fine for 1 ride after dealer worked on the sled. All of these codes are related to the ISC Ckt as best I can tell. Is there a way to clear those codes without getting it to start! Looking for some help please!
Blue

 

[Bluebullet]

I have a 2015 Viper LTX that has been brought to me to see if I can find the issue. Sled cranks fine, fuel pump comes on and pressurizes and shuts off. codes active are: P1689 (rev ckt low), P1692 ( fwd ckt low), P0562 (sys volt low) also the R is showing on the dash and backup buzzer alarming. I replaced the battery with and new one as the negative post was broken off. ( obvious issue) I have checked all the fuses and removed and reinstalled all the relays. ( no obvious corrosion). I cleaned and reinstalled the two ground wires above the primary clutch. This sled also has the MPI turbo modification. Lots of loose wiring job not tied down, looks like a 12 year old wired! The ECU was updated flashed by a dealer last year. Ran fine for 1 ride after dealer worked on the sled. All of these codes are related to the ISC Ckt as best I can tell. Is there a way to clear those codes without getting it to start! Looking for some help please!
Blue

Moving on down to look at the ECU wiring. Man that thing is not easy to get to! How do I get the sled in diagnostic mode to reset codes? any help is appreciated!
Merry Christmas!

 

[Bluebullet]

Figured out the diagnostic mode through gage pod ( didnt help). All tests are good going into the ECU nothing coming out..... ordered a used spare ECU for reasonable cost.

 

[MrSled]

Figured out the diagnostic mode through gage pod ( didnt help). All tests are good going into the ECU nothing coming out..... ordered a used spare ECU for reasonable cost.

Thats a strange one. I would think a new battery would have done it.

 

[Bluebullet]

Update, installed the different ECU ( same part #) I purchased as it was used for testing other bad ECU's and was supposed to be good. (Sled cranks fine, fuel pump comes on and pressurizes and shuts off. codes active are: P1689 (rev ckt low), P1692 ( fwd ckt low), P0562 (sys volt low) also the R is showing on the dash and backup buzzer alarming. My question is: why are the codes fallowing into the new ECU? Doesn't the ECU store the codes until cleared? Battery was disconnected during the install connected the battery and turned on and all same codes active on the different ECU. I am F###### stumped. Please help!!!!!

 

[MrSled]

Doesn’t fire up or no fire and only codes? Maybe @Srxspec can help.

 

[Bluebullet]

Doesn’t fire up or no fire and only codes? Maybe @Srxspec can help.

Correct cranks but no fire or sputter at all. Codes remain active. Owner told me when it was re-flashed they changed the voltage regulator also. Thanks Tom!

 

[Srxspec]

Swap throttle bodies with a different sled and see if it follows.

 

[Bluebullet]

Swap throttle bodies with a different sled and see if it follows.

Thanks for the advice however I don't have a spare set available. I am going to head down and check the rest of the wiring by Volt reg and harness. I find it hard that swapping to a different ECU that the codes remained active as soon as I turn the switch on.....

 

[Bluebullet]

So Currently have volt reg and ECU out of the sled so I can see the harness and wiring better. I found that behind the fuse panel it looks like the orange/white wire to the ISC fuse may be pinched. this would cause the current codes to be active as that is a common feed to ISC relay and other relays along with a feed to the ECU. I can't just splice repair so I need to remove the wire out of the box ? How can I repair???????

 

[Bluebullet]

Story continues...... opened the harness leg form fuse panel, wow many splice connections from factory here is an example ( orange wire, 4 wires spliced in to 8) I opened this connection because this wire is common to fuse and relays that could be causing most of my codes. turned out all connections read good continuity and the way through to ECU. ISC fuse wire was in question based of looking pinched wire, so I bypassed and installed a new fuse holder separate of the factory fuse box. continued to check other wires fuse box to ECU all reading good. so hooked everything back and turned sled switch on. all codes remain. wiggled and moved all the factory splice connections with no change and still no start!!!!!!! I did come across a weird one...... With kill switch in the off position the sled will still crank over using the start switch. WHY?????? the kill switch is turning off the gage/console but still allows the start ckt to run???? All my other sleds with kill switch off nothing ever happens! Can anyone please tell me if this is correct? ( Idoubt it) Please let me know. Thanks everyone!!

 

[Srxspec]

Yes, the sled will turn over with the kill switch in the off position. This is normal.

 

[qcmay]

Hello,
I suggest you inspect the battery fuse (30A) and holder. I had a problem like this, I don't remember the codes exactly but I had a burning smell after operating the reverse 3-4 times in a row. The burning smell came from this fuse holder. I had to install an external fuse holder as you did with the ISC fuse.

 

[Bluebullet]

Thanks QC and SRXSPEC for your time to answer my questions.
Update.... Put sled all back together and left on battery charger for awhile. Turned kill switch on and start sw on, took awhile for gage to come on but all clear no codes...... she started right up....let it run and warm up. Messed with fuse wires, gage harness connections, no change and sled kept running! Shut off and restarted 4 or 5 times. WTF again but at least I had it running. shut off sw and kill switch. came back 2 hours later went to start and ALL CODES RETURNED with no start! I have had enough and told my cousin to come and pick this lemon up! This morning I go out to the garage and guess what....... All codes clear when powered back up.......... Gremlin's overload! I have worked on a lot of equipment in my life but this one has been a struggle for sure! I hate to give up however it's time! I am not sure if the turbo electrical connections are effecting this or the starter or other sled loads are causing these failures! Thanks for everyone's suggestions and Help!
Terry