Ground question


Yeah, it was pretty stiff, but eventually a buddy
Jul 13, 2005
Granger, IA
Can't find the bolt to the back of the block for the small flat wire from the firewall. It also has a line from the wiring harness from the injectors. Where else can I hook the two wires to for a ground?
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Grounds are important to any electrical system, and especially to computers.

1.) The main power ground is from engine block to battery: it is the power ground for the starter & alternator.

2.) The secondary power ground is between the back of the intake manifold and the driver's side firewall. It is often missing or loose. It supplies ground for the alternator, A/C compressor clutch and other electrical accessories such as the gauges. Any car that has a 3G alternator needs a 4 gauge ground wire running from the block to the chassis ground where the battery pigtail ground connects.

Picture courtesy timewarped1972

3.) The computer has its own dedicated power ground that comes off the ground pigtail on the battery ground wire. Due to it's proximity to the battery, it may become corroded by acid fumes from the battery. It is a black cylinder about 2 1/2" long by 1" diameter with a black/lt green wire.You'll find it up next to the starter solenoid where the wire goes into the wiring harness

4.) All the sensors have a common separate ground. This includes the TPS, ACT, EGE, BAP, & VSS

5.) The O2 sensor heaters have their own ground (HEGO ground) coming from the computer. The O2 sensor ground (orange wire with a ring terminal on it) is in the wiring harness for the fuel injection wiring. I grounded mine to one of the intake manifold bolts

6.) The TFI module has 2 grounds: one for the foil shield around the wires and another for the module itself. The TFI module ground terminates inside the computer.

7.) The computer takes the shield ground for the TFI module and runs it from pin 20 to the chassis near the computer.

8.) The computer's main power ground (the one that comes from the battery ground wire) uses pins 40 & 60 for all the things it controls internally.

See for help troubleshooting voltage drops across grounds


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I know where all the grounds are, but I was just wondering if there was some other place on the block or intake I could place it? Like would one of the bolts that goes that holes the fuel rails farther apart work?
Any place that bolts to bare metal that is clean & shiney will do. All the metal of an engine assembly is an equal conductor as far as grounds go.