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Hammer Time
Hammer Time, L1 Master Technician
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1986 olds cutlass 307(y) auto to set timing the book says ...

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1986 olds cutlass 307(y) auto to set timing the book says to jumper pins A & B on diagnostic plug. on the lable decal on the fan shroud it says to ground the C-3 diagnostic lead. i can't find the C-3 lead. please help. thanks, john

Optional Information:
1986 Oldsmobile cutlass 307

Already Tried:

Set timing at low idle and Before Top Dead Center, unless otherwise specified. Disconnect and plug distributor vacuum line, as equipped, at distributor.

1982-86 1.8L (112) FI, 2.5L (151), 4.3L (260), 5.0L (307) engines, ground diagnostic connector.

1982-86 2.0L (122) FI, 2.8L (173) FI, disconnect EST bypass connector (single connector, tan/black wire).

1981-90 all others W/carburetor, disconnect 4-wire connector at distributor.

Timing MUST be set to specifications on emission label, if different from setting listed. If "Check Engine" light comes on during procedure, remove ECM fuse to clear.

According to these instructions, your vehiclle uses the "jump A and B" method.

Customer: replied 11 years ago.
Reply to Hammer Time's Post: don't know if last post went thru. 1986 5.0L VIN Y
for timing the manual calls for jumpering pins A&B on diagnostic connector (ALDL)it also states that due to late changes, always refer to Engine tune-up Decal in engine compartment before performing tune-up. " if manual and decal differ, use decal specifications." the decal states to;
1. disconnect thermac hose and plug it.
2. start engine and ground C-3 diagnostic lead.
3. set timing at spec. RPM in park. remove ground from C-3 diagnostic lead.
i can't find anywhere that states that the C-3 lead is the same as the A&B pins of the ALDL
There really seems to be some confusion with this proceedure. The connecter your looking for is a light brown single wire with a connecter to separate it. On some vehicles, it's behind the gloce box, on some others it's sticking out of one of the harnesses along the firewall. Since the instructions are saying it doesn't use one, it obviously doesn't tell me where it is.
Customer: replied 11 years ago.
Relist: I still need help.
1986 olds 5.0L 307
the manual states the following;
1.on the 5.0L VIN (_F_)
put EST into by-pass mode by unplugging "set timing" timing connector. Connector is a Tan/Black wire in the harness near the distributer. Set timing and reconnect "set timing" connector.
2. on the 5.0L VIN (_G&H_)
Unplug 4-wire connector at distributor. Set timing and plug in 4-wire connector.
3. on the 5.0L VIN (_Y_) which is mine. the tune-up decal on my vehicle states to ground C-3 diagnostic lead. Set timing then remove ground from C-3 diagnostic lead.
perhaps this info will help you help me in locating this C-3 lead. thanks again .john
I have spoken to a GM dealer tech and he informs me that you can use the A B method at the diiagnostic connecter and that will work also. You don't need to find that connecter.
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