PCM Connector: Blue (C1) 1998-99

1998-1999 Blue PCM Connector Pinout

In this article, you'll find the pin out descriptions of the 4 PCM connectors for the 1998-1999 GM 4.3L, 5.0L or 5.7L Engines.

NOTE: For other PCM pin-out charts, take a look at the following:

  • 1993 PCM Pin Out Chart (GM 4.3L, 5.0L, 5.7L GAS w/ 4L60-E).
  • 1994 PCM Pin Out Chart (GM 4.3L, 5.0L, 5.7L GAS with A/T).
  • 1995 PCM Pin Out Chart (GM 4.3L, 5.0L, 5.7L GAS with A/T).
  • 1996-97 PCM Connector Pin Out Charts (GM 4.3L, 5.0L, 5.7L).

Each connector can be identified as:

  1. C1 Blue (32 Pin Connector).
  2. C2 Red (32 Pin Connector).
  3. C3 Clear -or Grey- (32 Pin Connector).
  4. C4 Black (24 Pin Connector).

The symbol: <-> means that the connector pin # will have one of two different wires DEPENDING on the actual year of your vehicle or whether your it's equipped with a 4.3L, 5.0L, 5.7L, etc.

C1 (Blue) PCM 32 Pin Connector
Pin Wire Color Description
1 --- Empty
2 --- Empty
3 Brown w/ White stripe 1X Cam (CMP) Sensor Signal
4 --- Empty
5 --- Empty
6 --- Empty
7 Tan HO2S Low Bank 2 Sensor 1
8 Pink w/ Black stripe Cam (CMP) Sensor Ground (Low)
9 Purple Fuel Gauge (Fuel Level Output)
10 <-> --- Empty (1998 Only)
10 <-> Tan w/ Black stripe TCC Control Solenoid (1999 Only)
11 --- Empty
12 --- Empty
13 --- Empty
14 Brown AIR Relay Control (California Only)
15 Yellow w/ Black stripe Vehicle Speed Sensor (VSS)
16 --- Empty
17 --- Empty
18 <-> Purple w/ White stripe Dual Tank Fuel Module (1998 Only)
18 <-> --- Empty (1999 Only)
19 Purple w/ White stripe HO2S High Bank 1 Sensor 1
20 <-> Purple HO2S High Bank 1 Sensor 2 (1998 Only)
20 <-> Purple HO2S High Bank 2 Sensor 2 w/out C6P -under 8600 GVW (1999 Only)
20 <-> Purple HO2S High Bank 1 Sensor 2 w C6P -over 8600 GVW (1999 Only)
21 Purple HO2S High Bank 2 Sensor 1
22 <-> Purple w/ White stripe HO2S High Bank 2 Sensor 2 (1998 Only)
22 <-> Purple w/ White stripe HO2S High Bank 2 Sensor 2 w/ C6P -over 8600 GVW (1999 Only)
22 <-> Purple w/ White stripe HO2S High Bank 1 Sensor 2 w C6P -under 8600 GVW (1999 Only)
23 --- Empty
24 <-> Tan HO2S Low Bank 1 Sensor 2 (1998 Only)
24 <-> Tan HO2S Low Bank 2 Sensor 2 w/out C6P -under 8600 GVW (1999 Only)
24 <-> Tan HO2S Low Bank 1 Sensor 2 w/ C6P -over 8600 GVW (1999 Only)
25 Tan w/ White stripe HO2S Low Bank 1 Sensor 1
26 <-> Tan w/ White stripe HO2S Low Bank 2 Sensor 2 (1998 Only)
26 <-> Tan w/ White stripe HO2S Low Bank 2 Sensor 2 w/ C6P -over 8600 GVW (1999 Only)
26 <-> Tan w/ White stripe HO2S Low Bank 1 Sensor 2 w/out C6P -under 8600 GVW (1999 Only)
27 --- Empty
28 Purple Crank (CKP) Sensor Ground (Low)
29 Light Green w/ Black Vehicle Speed Sensor (VSS) Low
30 Purple w/ White stripe Vehicle Speed Sensor (VSS) Signal
31 Yellow 4X Crank (CKP) Sensor Signal
32 --- Empty

Safety Precautions

Here are some very important safety precautions when testing the wires coming out of the PCM connectors.

  1. If one or any of the wires on your GM vehicle DO NOT match the color stated in the Pin Out Charts, then you should not use the Pin Out Charts in this article. Why? Because this is the clearest indication that these ARE NOT the Connector Pin Out Charts for your particular vehicle.
  2. Never probe the front of the connector.
    • You should use a wire piercing probe and probe the wire a few inches away from the connector.
      • To see what this tool looks like: Wire Piercing Probe.
    • You should use a back probe.
  3. You should never disconnect any of the PCM connectors without first disconnecting the battery negative (-) terminal.
  4. This is a FLASH unit and requires reprogramming if replaced with a new one or used one.

Disclaimer

I've spent many an hour double, triple, and quadruple checking these pin out charts (in these page and in the next couple of pages) using the best sources to compile it but nothing in life is perfect. I don't have a staff of proof readers or editors (or even volunteers), I'm just a little guy typing this stuff up in my spare time to help and give back to the Do-It-Yourself community. So without further ado, here's my disclaimer:

© copyright Abraham Torres-Arredondo: This information is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

If you do spot errors, please let me know. You can use the contact form at the end of the article.

PCM Connector Pinouts