PHASTC5

1999 shut down at 75 mph. No restart, towed home (2 nd time/ 6 mo) same thing. Get it off the truck, and starts right up and runs fine. This time it set codes.
99HVAC , one code BO338HC

AO LDCM, 8 codes: B2208,B2282H,U1255H,U1064H,U1016H,U1096H

A1 RDCM, 6 codes: B2283H,B2285H,U1255H,U1064H,U1016H,U1096 H

BO RFA 3 codes: U1096H,U1064H,U1016H

I have complete set of service manuals, but sure could use some help. The car has never let us down in the 60K miles since I got it. I did check fuel pressure first, and have 55-60 PSI at rail.
Where do I start??

Got uid0

Have you inspected your belt to make sure it is not slipping?

Also sounds like it could be a loose ground. Read the posts on electrical issues here. It should be very helpful.

The hvac code you have can come up after a power loss.

I hope you do not have the stock ac/delco leaking battery that has dripped down on to the computer and wiring causing a big mess.

uncle52

get a handle on the DIC codes first. you can google the info or go to search on this forum, enter DIC codes and hopefully you get answers. As to why it starts up after the ride, i'd take a look to see if your starter is working right or staying activated, gets hot, then cools down enough to work again. just a thought. good luck and let me know what happens.

PHASTC5

I have my 2 nd Altima Battery and use a solar charger on it when parked. Found out the hard way that a dry battery doen't like to go dead. I will be checking out all ground connections.
Thanks for your help
PHASTC5

PHASTC5

Starter works great. Even in neutral coasting down I-5 at 70 mph. I do believe I set off the Transmission Range code due to me truying to start while coasting.
Thanks for the help
PHASTC5

PHASTC5

After reading most of Volume 3 of the service manual I found serveral of my codes direct me to the Serial Data Line. I hope to find some connection problems. Seems Northern CA only gets rain this year, so Corrosion may be the issue.
Thanks, PHASTC5

PHASTC5

No, The Vette Club I was Pres. of found out long ago to replace that stock battery with a dry cell.
Thanks for the thought
PHASTC5

PHASTC5

I will be checking all grounds thanks to the download of locations found on this forum last night.
Thanks, PHASTC5

f6john

I have experienced the starting right up after unloading from the rollback twice although on a different GM vehicle. It was the fuel pump. Just because the pressure shows good at a given point doesn't rule out a possible problem either. Just keep an open mind about the pump as a possibility.

sprayed1998

Its the ground on the drivers side of your block, under the header. I can almost guarantee it. Do yourself a huge favor and check that 1st.

Silverbullet00

This CF Member is DEAD ON! The ground is called G105 and is located under the block on the driver's side just like he said,,,,codes 1096, 1064, 1016 are all right there,,,,,believe me I know!


May not be all of your problems but my $$$ are on that ground point...Gave me fits for quite a while.

lucky131969

Hmmm....communications codes and G105, huh? G105 provides a ground for SP122, which in turn, provides grounds for the fuel pump, oil level, and O2 sensors.

Got uid0

I still think it sounds like a bad ground.

Do you have a link for the solar charger or can provide the charger name?
I know that the optima's have to be charged at a very very low amount.

Silverbullet00

Since when does the C5 system makes sense ground wise? All I am trying to do is give the OP some direction. My car shut off on the highway just like his,,,two years ago,,,it was an intermittant ground loss to the fuel pump,,,,removing, cleaning and reinstalling G105 fixed that and a few other problems that the service manuals never even mentioned. When your grounds have a weak link thrown codes can not be trusted all the time,,,,,just trying to help,,,,Hmmmm

lucky131969

I see. I'll keep that in mind.

PHASTC5

Thanks for the direction. This Forum is great.

Bill Curlee

OK,, Ill throw my 2 cents in! Seeing how you have U DTCs, and there on the LDCM, RDCM & RFA,, I be willing to bet that you have a poor CONNECTION in one or BOTH of your DOOR WIRING HARNESSES CONNECTORS!

Here’s the deal. Pop the accordion tube out of both doors:





Once you get the accordion tubes popped out of the door and door frame, pull the wiring harness connectors out of the door frame A pillar hole. Once you have them out, un-plug the connectors and inspect ALL the pins (MALE & FEMALE) Look for damage, corrosion and deformation.

On this connector, (power plug) the female pin on the TOP ROW "center pin), is deformed. The little metal tong is bent down and will cause a poor intermittent connection. When the module gets power interruptions or spikes in power, it causes CAOS on the serial data line and the modules can NOT COMMUNICATE properly. It can and will cause the car to shut down.

Sounds simple enough but, this issues has stranded me more than once before we figured out what caused it. Sometimes just shaking the hell out of the accordion tube/wiring harnesses will be enough to get you back on the road!. I’ve even seen it fix its self when you close and open the door!

Just re-bend the little metal tong back in place and carefully reconnect the connectors (with the rubber accordion tube back on ) and see if that resolves that issue.




Having a low charge on your battery and or a weak battery can and will leave History U series DTCs. The U-series DTCs happen immediately during the crank session because your battery voltage drops LOW enough for some modules to shut down because of a B+ voltage below 9 VDC!
If your battery is low or needs to be replaced, get it recharged or replaced.

Got uid0

Does this only occur at certain speeds?

Possibly speed sensor damage or unplugged on the wheel bearing?

Bill Curlee

No Neither one will kill the engine..

PHASTC5

I checked the fuel pressure at a point when the car was not starting. I had 55 psi then. Do you still think it could be a pump problem? I depressed the schrader valve releasing the pressure, then keyed on the pump to reestablish and got the 55 psi.