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I have a 2000 Bonneville SLE with 97,000 miles on it. the car has been garage-kept and follows the recommended service guidelines.
I’ve had some problems in the recent past with the electrical system (replaced 2 bad ignition coils, replaced the ICM, and replaced spark plugs & wires). These dealer replacements cured some performance problems and cleared several OBD-II codes I was getting.
Now I have a new problem (or problems).
Lately on a cold start, the starter cranks and the engine tries to fire, but within a second or two the engine shudders, sputters, and ultimately dies. After two or three tries the engine fires up and runs just peachy. And on a warm start, behaves as expected.
But I’m getting two OBD codes being thrown – DTC C1298 (PCM Class 2 Serial Data Link Malfunction) and DTC P1626 (VTD Fuel Enable Signal Loss).
I’ve been doing some research online and here’s what I’ve found. (Why the Academy Award Winners at my dealership couldn’t do this is beyond me. Maybe they can’t read a fault tree, or maybe they just like to throw parts at problems and run up the invoices – see above). Please tell me if I’m on the right track.
The PCM and the BCM communicate at ignition, and if there are faults detected between the two modules, a fail condition is set at the VTD and fuel flow is restricted for ignition. Several retries of the ignition may clear the miscommunication and the thrown fault code is disregarded but stays in the computer.
This tells me that the problem may lie (a) with a failing or failed PCM, (b) a failed or failing BCM, (c) the wiring between the two systems.
Now most of my research tends to point to the PCM. But since I’m not giving my local dealership any more than the nearly $1K I’ve paid them to get to this point, I need to ask you experts online several questions.
1. Am I way off base on my non-expert diagnosis? Am I missing something?
2. In your opinion what is the MOST LIKELY CASE? Is it a failed or failing PCM?
3. What is a good, economical replacement-brand PCM and what does it cost?
4. Where is the PCM for the 2000 Bonneville SLE located, and can a DIYer replace it? What tools are needed?
5. If the PCM is replaced, will my PK3 keys still work or will I need to perform a security relearn procedure? How is that done?
6. Why do the auto makers make this crap so difficult?
Thanks in advance for any help you can provide. And sorry for the density of the post and number of questions. But I can’t get a coherent response from anyone else I’ve asked.
Happy New Year.
To jump right towards the end of your questioning…There is NO economical replacement PCM. If you choose to go aftermarket in that category, you’ll be bashing yourself in the head while screaming ‘why didn’t I replace it with a factory part!’ after it fails again and again and again!
If you do need a PCM, you wouldn’t be able to do it yourself anyway because it needs to be programmed to your vehicle. That can ONLY be done at a dealership, so you may as well fork over the money for a GM part and a GM dealer to do the job if you want it done right. It may sting a bit, but you’ll thank me later.
Now, as for your problems, which may or may not be computer related. The extended crank/no start until after a couple tries when cold sounds more like a fuel or ignition problem. Have you checked to see if the fuel pressure regulator is leaking? That is a very common thing to go bad on your car and will cause the problem you describe. Otherwise, possibly a crank sensor, ignition module, etc. Hard to be specific in any one area since I’m not working on the car in person. I’d also recommend a fuel pressure check. If your fuel pump is on its way out, low pressure and hard starting would be more evident when cold, like how you experience it now.
As for any electrical concerns, how about an ignition switch? Another very common problem area on your vehicle. A faulty switch can set the communication and fuel disable codes you are getting. I really doubt you have a bad BCM or wiring problem unless you’ve tapped some aftermarket equipment into the factory wiring somewhere.
That’s about all I can really think of that has problems on your car. Check those things out and I’m sure you’ll come across the problem in one of those areas. Good Luck!
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