Restore Your GMC Safari’s Reliability and Performance
Is your 2004 GMC Safari giving you headaches with unpredictable stalling, a persistent Check Engine light, or a frustrating no-start condition? Before you start replacing expensive sensors or fuel system components, the root cause is often the vehicle’s brain: the Powertrain Control Module (PCM). As a technician with over two decades of experience, I’ve seen countless GM vans from this era develop these exact issues. The constant heat and vibration in the engine bay, especially near the battery, can degrade the sensitive internal circuits of the original PCM over time, leading to baffling problems that come and go.
This isn’t just a replacement part; it’s a reliable, long-term solution. We take the guesswork and hassle out of the repair by pre-programming this module specifically for your vehicle. Simply provide us with your VIN during checkout, and our experts will flash the unit with the latest, most stable GM factory software. This ensures perfect communication between your engine and transmission, restoring the smooth operation and fuel efficiency you expect from your van. A properly functioning 2004 GMC Safari PCM is critical for everything from ignition timing to transmission shift points.
A Technician’s Notebook
I remember a 2004 Safari that came into the shop towed in. The owner had already replaced the fuel pump and crank sensor trying to solve an intermittent no-start problem. The van would run fine for days, then refuse to start, with no spark and no fuel pump prime. After checking all the wiring, I put a heat gun on the PCM for about 30 seconds. Sure enough, the van wouldn’t start. After it cooled down, it fired right up. It was a classic case of thermal failure inside the module. We installed a pre-programmed PCM, and the customer called back a month later to say his van had never run better. This simple swap saved him from more wasted time and money on incorrect diagnoses.
Common Signs of a Failing Engine Computer
- ✔ Check Engine Light is on with codes like P0601 (Internal Control Module Memory Check Sum Error) or P0606 (ECM/PCM Processor Fault).
- ✔ The engine cranks but refuses to start.
- ✔ Unexplained stalling or stumbling, especially when the engine is warm.
- ✔ Noticeable decrease in fuel economy.
- ✔ Harsh or erratic automatic transmission shifting.
- ✔ Failure to pass an emissions or smog test.
- ✔ Communication errors with diagnostic scan tools.
A Straightforward Guide to Installation
- ✔ Safety First: Always disconnect the negative terminal from your vehicle’s battery before beginning work.
- ✔ Locate the PCM: On your 2004 GMC Safari, the PCM is located in the engine compartment on the driver’s side, right next to the battery tray.
- ✔ Disconnect Connectors: Carefully unclip and pull back the levers on the large multi-pin electrical connectors to release them from the module. Avoid forcing them.
- ✔ Remove the Old Module: Unbolt the PCM from its mounting bracket. It’s typically held in by a few small bolts.
- ✔ Install the New Module: Seat your new, pre-programmed PCM into the bracket and secure it with the mounting bolts.
- ✔ Reconnect Everything: Firmly plug the electrical connectors back into the new module until they click into place. Reconnect the negative battery terminal.
- ✔ Final Procedure: While this 2004 GMC Safari PCM is plug-and-play, some GM vehicles may require a simple security relearn procedure, which takes about 30 minutes and involves cycling the key. Instructions are readily available online or in your owner’s manual.
Verified Vehicle Compatibility
This module, part number 12586243 (also replaces 89017739), is a direct-fit for a wide range of 2004 GM vehicles. Please verify your specific model and options below.
Vans:
- ASTRO 04 (LH front by battery)
- EXPRESS 1500/2500/3500 VAN 04 (LH rear engine compartment)
- SAFARI (GMC) 04 (LH front by battery)
- SAVANA 1500/2500/3500 VAN 04 (LH rear engine compartment)
Trucks & SUVs:
- AVALANCHE 2500 04 (LH front under battery)
- BLAZER S10/JIMMY S15 04 (RH front engine compartment)
- ENVOY XL / ENVOY XUV 04 (5.3L, next to air box)
- RAINIER 04 (5.3L, next to air box)
- S10/S15/SONOMA 04 (RH front engine compartment)
- SIERRA 1500/2500/3500 PICKUP 04 (Gasoline, LH front under battery)
- SILVERADO 1500/2500/3500 PICKUP 04 (Gasoline, LH front under battery)
- SUBURBAN 2500 04 (8.1L, LH front under battery)
- TRAILBLAZER EXT 04 (5.3L, next to air box)
- YUKON XL 2500 04 (8.1L, LH front under battery)
Cars:
- CORVETTE 04 (RH engine compartment, ID 12586243)
- CTS 04-05 (V-Series, RH engine compartment, ID 12586243)
- GTO 04 (Main, LH engine)
- SSR 04 (Next to air box)
Choosing this pre-programmed 2004 GMC Safari PCM is the smartest way to get your vehicle back in top shape without the high cost and inconvenience of a dealership visit.
Frequently Asked Questions
What exactly does the PCM do?
The Powertrain Control Module (PCM) is the central computer that manages your vehicle’s engine and transmission. It controls fuel injection, spark timing, emissions systems, and automatic transmission shifting to ensure optimal performance and efficiency.
Do I need to program this module myself?
No. This is a key benefit of our service. We program the module to your vehicle’s specific VIN before we ship it to you. It arrives ready for installation, saving you a trip to the dealership.
What information do you need from me after purchase?
We will need your 17-digit Vehicle Identification Number (VIN). This is crucial for us to load the correct GM software for your specific vehicle configuration.
Will this fix my check engine light?
If the check engine light is caused by an internal failure of the old PCM (like codes P0601, P0602, P0606), then yes, this part is the correct fix. It’s important to properly diagnose the cause of the light before ordering.
Is this a difficult part for a DIYer to install?
For most individuals with basic hand tools, this is a very manageable job. On the 2004 Safari, the PCM is easily accessible next to the battery. Following our guide, most people can complete the swap in under an hour.
What if my original part number is 89017739?
This module is a fully compatible replacement for part number 89017739. It will function identically and is a direct interchange.