Have no crank, no dash warning lights. Where do i start?

Oldchevyguy

Well-Known Member
I'm hoping that some of you that are good with diagnostics can help me.

With battery hooked up, and full voltage , I have horn , brake lights turn signals. There is power and the diagnostic connector.
Nothing happens except some relay clicking at the BCM, key on, and I do not hear fuel pump. No Crank either (clutched pushed in)
A flow chart would be great. Any ideas?
 

Lonny

Administrator
Staff member
I would check for continuity of the tan twisted data wires.
They start at the OBDII connector and end at the ECM.
Make sure that tan with a black stripe at the OBDII is hooked to the tan with the black stripe at the ECM.
Do the same with the tan data wires with no stripe.

The data wires daisy chain through several modules and change colors twice.

Starts at the:

OBDII
tan and tan/black twisted


Power steering
tan and tan/black twisted - in
then brown and brown/black twisted - out

BCM
brown and brown/black twisted - in
then tan and tan/black twisted - out

If this were an automatic it would go to the engine harness and then back out to the ECM, manual transmissions don't do this.


ECM is always last
tan and tan/black twisted



I would also check your grounds.
 

Oldchevyguy

Well-Known Member
I would check for continuity of the tan twisted data wires.
They start at the OBDII connector and end at the ECM.
Make sure that tan with a black stripe at the OBDII is hooked to the tan with the black stripe at the ECM.
Do the same with the tan data wires with no stripe.

The data wires daisy chain through several modules and change colors twice.

Starts at the:

OBDII
tan and tan/black twisted


Power steering
tan and tan/black twisted - in
then brown and brown/black twisted - out

BCM
brown and brown/black twisted - in
then tan and tan/black twisted - out

If this were an automatic it would go to the engine harness and then back out to the ECM, manual transmissions don't do this.


ECM is always last
tan and tan/black twisted

Could I first check these wire continuities between aldl diagnostic connector and pcm? Or do they have to done separately?

I would also check your grounds.
 

Oldchevyguy

Well-Known Member
Ok. So I checked continuity with all the serial data wires. I expected a problem with the front to rear, or BCM to PCM ones. These are the ones that are lengthened. They were good. Next, BCM to power steering control unit. Brown and brown/white. BINGO! No continuity with brown/white. I repaired it with a new wire run outside the harness.

Now I have KO the security light (padlock). Pushed the unlock button on the fob, and now it goes away after a few seconds. BUT NOTHING ELSE ON THE DASH LIGHTS UP.. Also no crank no fuel pump running. ANY IDEAS??? BTW. I checked all the grounds.
 

baustin

Well-Known Member
Are all of the connectors on the bottom of the fuse block actually seated/tightened together? If you set the fuse block in place but didn't tighten the screws to pull the connectors together then I think you get that response.
 

Oldchevyguy

Well-Known Member
Are all of the connectors on the bottom of the fuse block actually seated/tightened together? If you set the fuse block in place but didn't tighten the screws to pull the connectors together then I think you get that response.
Thanks for the response. Sure there tight.
 

Oldchevyguy

Well-Known Member
Where did you run the repair data wires from and to.
Lonny, I replaced the brown/white wire between the power steering plug and the BCM plug C2. It tested open. All other serial data wires tested ok point to point as you suggested.
 

OptimizePrime

Well-Known Member
Check your BCM/ECM fuses.

Tighten down the ECM bolts really nice and tight.

Do you have 12v at the starter / ECM prong?

Did you paint your block where the starter mounts? It self grounds
 
Top