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Discussion Starter #1
What does ALDL stand for? I'm swapping this 88 TBI in my Jeep. Also, What's an EAC solenoid? Is it required? An Emissions thing? Can I use the orig ECM/Prom - original was 350 w/TH400, whereas current is 350 w/SM465. Do I need to install a VSS for this as well? And lastly, with regards to the Park/Neutral Switch, can I wire that to a switch on my Clutch Pedal so that the engine will not start unless the Clutch is pushed in (seems logically correct)?

Thanks,
Chris
 

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ALDL... Assembly Line Diagnostic Link. That is where you plug in the code scanner. Keep it to help make troubleshooting a whole lot easier.
 

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Discussion Starter #3
Hrm, only problem is I don't have the connector. That was not included in my purchase...dude musta cut it out on/for me. Such a nice guy....:rolleyes:

Chris
 

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Did you mean IAC? I dont know what an EAC is.
IAC = idle air control.

If you can get the ECM from a manuel. They go for as little as $30 I've been told.


Charlo
 

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Discussion Starter #5 (Edited)
No, I meant EAC. I know what the IAC is.

Actually, the ECM is the same, only the PROM is different. I have a few BIN files I downloaded for trucks with manual trans....but have no way of burning them at the moment.

Chris
 

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You didn't say what the harness is out of, but at least on the R/V series for '88 (old body style Suburbans, Blazers, and crew cabs), the ALDL was connected to a 6-pin connector that was ~10" from the 2 computer connectors. The check engine light and VSS were also hooked in through this connector.

No, the clutch switch needs to be wired into the starter circuit. I don't think I'd want one in an off-road Jeep anyway.

Pete
 

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Discussion Starter #7
The harness is out of an 87 or 88 G30. It's what the engine came out of. My harness does not have a VSS connector. It does have a couple connectors that went to the trans, so I'll have to look more closely. I don't have the TH400 anymore, but I'm betting that the trans did not have a VSS on it either. I have some pics of it somewheres and will have to dig into it.

I'm betting that I can run this with the orig EPROM and not get one from a manual. This is what I'm going to try first anyways. I have to know and if it don't work, then I'll buy the cables and burning and do it all myself.

I thought about this some more and I'm going to tie the P/N switch to ground, so that it'll start while in gear if I need it.

I'll have to rob a junker for the ALDL connector and wire it per the schematic I have...

Chris
 

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The P/N switch has nothing to do with starting the engine.

Pete
 

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Discussion Starter #9
From what I understand, it does. The ECM won't allow the engine to start unless it's in Park, or Neutral (connection to GND).

Please, follow up your comment with rationale on why you think the P/N switch does not...

Chris
 

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Are you thinking that the engine won't turn over, or that it will turn over but not fire or spray fuel without the p/n wire hooked up?


Pete
 

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Discussion Starter #11
originally, I was thinking the first, but now leaning towards the latter. This is because I got my hands on an 81 CJ7 harness this weekend that was made for the GM 4cyl. I installed it into my 79 CJ7 that's got the 350TBI and successfully got it to crank over! I still need to finish piecing the wiring harness together, and run new fuel lines, but the light at the end of the tunnel is in sight!

Back to your email...I think the latter would be true. Not only would a new model truck not allow the engine to turn over without the clutch pedal pushed, or the tran in P/N, but believe the input to the ECM prevents it from allowing ignition. Fuel will still spray because the pump runs for 3-5 secs regardless of P/N status...

Chris
 

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The park/nuetral switch has no effect on the ability of the vehicle to run.this is the input for the ecm to tell it is in gear and raise the idle.This also when the ecm starts to look at vss input for fuel and timing map adjustments. You can just ground the p/n wire and not run a vss and it would work ok. for best performance, hook up the p/n sw. and run a vss. Brett
 

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What the Noob said. :flipoff2:

Early TBIs (not sure about the later ones) had no electrical interlock on the crank circuit, when the shifter is not in P or N there is a mechanical interlock that prevents the linkage from the key switch from being able to go all the way to "start". The P/N switch at the bottom of the column that was used as the electrical starter interlock (which was redundant) on carb'd trucks was used for the ECMs P/N input instead when they went to TBI.

Also, fuel will not spray when the motor is not turning over, the ECM uses the signal from the distributor to fire the injectors. Just because the pump is running, does not mean fuel is spraying.

Pete
 
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