Electrical 2000 GT Intermittent Engine Shutdown In Motion - DTC U1262

[kenster1092]

Hi, it's me again.

Last time I was here I posted about a spark plug blowout problem and consequent overly rich fuel delivery issue that I have fixed with the help of you, the community.

I have a new, very intermittent problem

When driving over bumps, particularly ones that are hard (I have a lowered car with stiff suspension, so hard can sometimes be bumps that are nothing for you) there is a very random chance that the engine will shut down, with an equal chance of randomness in the gauge odometer going to all dashes (--------). Sometimes in this intermittent issue the engine will shut down but the gauge cluster acts normal. Shifting to N and cycling the ignition works to get the engine started in motion again.

The only DTC I get when pulling codes with Forscan is a U1262, and the only advice it gives is to "run self-test" and "fix all relevant DTCs then clear codes and retest". Not particularly helpful in helping me figure out where could this problem stem from.

Any ideas?

 

[squeak93]

Start checking the basics. Grounds, connections etc. The fact that it's happening on a jolt points to this. ECM in pass footwell would be a good place to start connection wise then look over everything.


Are you sitting on the rear bump stop to cause it to be so "violent" on a bump - or have worn/bottomed out shocks? Fix the cut-out issue - almost positive its a connection problem then fix the ride or you'll compound with broken mounts/torque box issues etc.

 

[kenster1092]

Start checking the basics. Grounds, connections etc. The fact that it's happening on a jolt points to this. ECM in pass footwell would be a good place to start connection wise then look over everything.


Are you sitting on the rear bump stop to cause it to be so "violent" on a bump - or have worn/bottomed out shocks? Fix the cut-out issue - almost positive its a connection problem then fix the ride or you'll compound with broken mounts/torque box issues etc.

I will be replacing the front sway bar end links as one side has a bushing that's about to separate from the car, so when it's on stands I will check the grounds and connections from the PCM while I'm under there and inspect the HEC connections.

I have reason to believe the problem is from either the HEC or the PCM. Though with the DTC being a generic SCP Communication Fault code without specifying the module acting weird, it's hard to say for sure. I don't think a loose ABS Module, CCRM or GEM connection can cause engine shutdown after a bumpy jolt, but I'm always happy to be proven wrong as I am still really new to the SN95 platform.

FWIW, I did a self-test on the HEC and the dtc portion pulled 2 codes:

• D262
• 5284

As for the ride, I don't think I am bottoming out. The car is lowered and is on aftermarket shocks and springs, the rear could just be stiffer than usual because the previous owners of this car was trying to mod it out to what I think is a street-legal track car. I can take photos of how it sits and the rear suspension with wheels off and send either in DM or in a new topic once I fix this intermittent issue - the previous owner did not list out the aftermarket suspension parts, so that's on me for not pressing what has changed before pulling the trigger on this one.

 

[kenster1092]

Well I did something and the issue no longer manifests itself. Been daily driving my New Edge since the last post and the car no longer intermittently shuts down on bumps jolts.

I did:

• Check the PCM and wiring surround the PCM in the passenger kick panel
  • The green plug had some bluish green corrosion on the contacts
    • I took some contact cleaner and sprayed it on the contacts, let it sit, wiped it off, and replugged
• Check the PCM itself
  • The module itself is loose and unsecured. So are the rest of the plugs in the kick panel
    • The plug connection itself on the PCM is really tight. It's just that the module is loose and somewhat dangling since there's nothing to hold it to the body.
    • Makes me think the previous owners have been heavily messing with the electronics. I did what I could to help secure the PCM, but I think I'm missing a metal bracket.
• There was a stray black wire that was open. Not sure where it leads to as I didn't open up the flooring
  • I wrapped the open end with electrical tape and also folded it inwards with the plastic trim as I reinstalled the trim, to help ensure it does not contact any metal

Also replaced the front sway bar end links and ride quality did improve, took the car in for a front wheel realignment and the ride has drastically improved (had lots of negative camber and toe-in on both wheels), including navigating bumps. Never shut down again since.

 

[squeak93]

Pcm should have a bracket and two bolts to hold it to some Jnuts in the body to keep it from bouncing around etc.

You can see them in this unrelated wiring pic: