ground locations

[ss#4]

Hello, does anyone have a chart or figure that describes or shows the physical location of the ground locations for a 1999 GMC/Chevy K1500 pickup?

[procaddytech]

For any particular system? There are over 20 grounds listed for a 1999 K truck with almost as many illustrations.

[ss#4]

I am trying to work out an issue with a missfire and the security light. NONE of the normal fixes are working. Thought I would clean all the grounds associated to those circuits. thanks for any help

[j cAT]

Originally Posted by ss#4

I am trying to work out an issue with a missfire and the security light. NONE of the normal fixes are working. Thought I would clean all the grounds associated to those circuits. thanks for any help

what miss fire code do you have ?

whats up with the security lite ? explain !

[ss#4]

Code is P0300. random misfire the plugs are black soot. Thus far I have changed the Plugs, Cats and fuel injection spider. Plugs as a cheap check incase fuel fouled. the 5 and 7 injectors were leaking and the cat was mariginal on one side. I have also verified the cap and wires are good and it is a new distributor. MAP sensor reads 20 and manifold vacuum with a guage is the same. Compressioin is good and the leakdown numbers are fine. The ECU was replaced with a slightly tuned one that eliminates the passlock system, since all the other bypass fixes didn't work with the original computer. I have also verified the coolant sensor is good. All plugs are getting fire, although 5 and 7 are a little eratic. Fuel pressure is also fine. measuring the exhaust temp Bank 1 is 325 and Bank 2 is 150. I believe this is telling me 1 is lean and 2 is rich, O2 say the samething .8/.2 However all plugs are black. Any thoughts?

[ss#4]

oh and no apparent vacuum leak. I spray the outside with brake clean and pulled the crank case breathers and no vacuum there either.

[j cAT]

Originally Posted by ss#4

oh and no apparent vacuum leak. I spray the outside with brake clean and pulled the crank case breathers and no vacuum there either.

I would pull the distributor and check for any bearing issue and the cam gear to it.

How many miles on this engine ?

Did you remove and measure /inspect the ignition wires for proper resistance/routing/insulation damage?

one side of the exhaust is low / what about a compression check.

I am guessing you have multi issues with this.

when you say NEW on components , IS THIS NEW TO THIS ENGINE or new NEVER USED BEFORE ?

[procaddytech]

Have you replace the O2 sensors? If one is stuck lean or does not crosscount the ECM will believe the O2 and think the engine is lean and keep adding fuel to try to get the O2 to swing. Especially if one bank is fouling plugs and the other is not. Since each bank has its own engine monitoring O2, each bank can be affected differently. Do the front O2 sensors swing above and below 450mV quicky?

[ss#4]

Originally Posted by j cAT

I would pull the distributor and check for any bearing issue and the cam gear to it.

How many miles on this engine ?

Did you remove and measure /inspect the ignition wires for proper resistance/routing/insulation damage?

one side of the exhaust is low / what about a compression check.

I am guessing you have multi issues with this.

when you say NEW on components , IS THIS NEW TO THIS ENGINE or new NEVER USED BEFORE ?

the motor has 130k on it. yes New means new out of the box. so unless the parts are defective from the manufacturer.

[ss#4]

Well I verified what the shop compression check and evidently they did not check every cylinder. The #6 cylinder is completely dead, which explains the low temp on that bank. leak down shows the exhaust valve is leaking.

However I don't quite understand the misfire in 5 and 7. leaving the #6 plug out and starting the truck the miss in 5 and 7 is minimized but not eliminated. Leakdown for 5&7 is with in 10%