Restore Your Truck’s Brain and Get Back on the Road
As a technician with over two decades of experience under the hood, I’ve seen countless trucks and vans sidelined by a faulty Powertrain Control Module (PCM). If your 1998-1999 GM vehicle is experiencing frustrating issues like stalling, erratic shifting, a persistent check engine light, or a complete no-start condition, the problem often traces back to this critical component. The PCM is the electronic brain of your engine and transmission, and when it fails, it can cause a cascade of problems that are frustrating to diagnose. This isn’t just a part; it’s the solution to getting your reliable workhorse back in service.
This is a quality, tested used PCM, part number 9355699, sourced from a salvaged vehicle. The real value here is our professional programming service. Before this module ships, we flash it with the latest GM software updates using the specific Vehicle Identification Number (VIN) from your truck or van. This means it arrives at your door ready for installation, saving you a costly trip to the dealership and the high price of a new unit. You’re not just buying a part; you’re buying a complete, plug-and-play solution. This service ensures compatibility and proper communication with all your vehicle’s other modules, restoring the performance and reliability you depend on.
Case Study: A Tricky Diagnosis
I remember a ’99 Tahoe that came into the shop on a tow truck. The owner had replaced the fuel pump and relay, but it still wouldn’t start—it had spark but no fuel pressure. The diagnostic scanner couldn’t even communicate with the old PCM. After confirming power and ground to the module, we suspected an internal failure. On these older GM PCMs, it’s common for the driver circuit that controls the fuel pump relay to burn out. We installed one of our VIN-programmed modules, performed the security relearn, and the Tahoe fired right up on the first try. The customer saved hundreds compared to the dealer quote and was back on the road the same day. It’s a classic example of how the right part, correctly programmed, makes all the difference.
Is Your Truck or Van Showing These Symptoms?
A failing PCM can manifest in various ways. If you’re noticing any of the following, it might be time for a replacement:
- ✔ Check Engine Light is on with codes like P0601 (Internal Control Module Memory Check Sum Error) or P0606 (PCM Processor Fault).
- ✔ Vehicle will not start or is very difficult to start.
- ✔ Poor engine performance, including misfires, rough idling, or stalling.
- ✔ Decreased fuel economy for no apparent reason.
- ✔ Harsh or incorrect automatic transmission shifting.
- ✔ Failure to pass an emissions inspection.
- ✔ Intermittent loss of communication with the diagnostic scan tool.
A Straightforward Guide to Installation
Replacing the PCM in these GM vehicles is a manageable job for a DIYer with basic tools. Our pre-programming service handles the most complex step for you. Just follow this process:
- Safety First: Disconnect the negative terminal from your vehicle’s battery to prevent any electrical shorts.
- Locate the PCM: On most trucks and vans covered here, the PCM is located in the engine compartment, typically on the driver’s side inner fender or near the battery.
- Disconnect Connectors: Carefully unclip and remove all wiring harness connectors from the old PCM. These connectors are color-coded, making re-installation simple. Avoid forcing them.
- Remove Old Module: Unbolt the PCM from its mounting bracket and remove it from the vehicle.
- Install New Module: Bolt your new, VIN-programmed PCM into the mounting bracket.
- Reconnect Everything: Firmly plug the wiring harnesses back into their corresponding colored slots on the new PCM. Reconnect the negative battery terminal.
- Perform Security Relearn (CRITICAL): You must perform the GM Passlock/VATS security relearn procedure. This typically involves turning the key to the ‘ON’ position for 10-15 minutes, then ‘OFF’ for 10 seconds, and repeating this cycle three times. This allows your vehicle’s anti-theft system to recognize the new PCM. Your truck will not start until this is completed.
Verified Vehicle Compatibility
This module is a direct replacement for service number 9355699 and several other interchangeable part numbers. Please verify your original part number or match your vehicle from the list below to ensure proper fitment. This unit fits a wide range of 1998 and 1999 GM models.
CHEVROLET 2500 PICKUP 98-99 (Gasoline, LH engine compartment)
CHEVROLET 3500 PICKUP 98-99 (Gasoline, LH engine compartment)
GMC 1500 PICKUP 98-99 (Gasoline, LH engine compartment)
GMC 2500 PICKUP 98-99 (Gasoline, LH engine compartment)
GMC 3500 PICKUP 98-99 (Gasoline, LH engine compartment)
ASTRO 98 (LH front by battery)
BLAZER S10/JIMMY S15 98 (RH front engine compartment, w/o build date opt ZN4)
BRAVADA 98 (6-262, 4.3L, w/o build date opt ZN4)
ESCALADE 99 (LH front engine compartment)
ENVOY 98 (RH front engine compartment, w/o build date opt ZN4)
EXPRESS/SAVANA 1500 VAN 98-99
EXPRESS/SAVANA 2500 VAN 98-99 (Gasoline)
EXPRESS/SAVANA 3500 VAN 98-99 (Gasoline)
ISUZU HOMBRE 98 (4.3L, w/o extended build date opt ZN4)
S10/S15/SONOMA 98 (6-262, 4.3L, w/o build date opt ZN4)
SAFARI (GMC) 98 (LH front by battery)
SUBURBAN 1500/2500 98-99 (Gasoline, LH front engine compartment)
TAHOE/YUKON 98-99 (Gasoline, LH engine compartment)
Frequently Asked Questions
Why do you need my VIN?
Your VIN is essential. We use it to load the exact, correct GM factory software for your vehicle’s specific engine, transmission, and options. This ensures seamless operation and avoids compatibility issues.
Do I need to do anything after installing this PCM?
Yes. After physical installation, you MUST perform the security relearn procedure (VATS/Passlock). This is a simple process that pairs the new PCM to your vehicle’s anti-theft system and does not require special tools. Instructions are widely available online and are included in our guide above.
Is this a new part?
No, this is a high-quality, tested used part that has been sourced from a salvaged vehicle. This allows us to provide a reliable, cost-effective solution compared to a new dealer part.
What if my original part number is different but on the cross-reference list?
You’re good to go. GM uses several part numbers for the same hardware family. As long as your original part number (e.g., 16266645, 16250279) is in our fitment list, this module will function correctly once programmed to your VIN.
How long does the programming take?
Once you provide your VIN after purchase, we typically program and ship the module within one business day. Our goal is to get you the correct part as quickly as possible.