Diagnostic Mode

Jimmy

Banned
What exactly does the ECM command when the A and B terminals are jumpered,before the engine is started? (Like jumper it with the engine off then start it up jumpered)

What could happen if you did a WOT pass in diagnostic mode?
 

TYTILIDIE

METH HEAD
Re: Diagnostic Mode

I know htat the ECM goes into field test mode and it will run like crap. Why would you want to do that? Are you trying to read codes while you are driving? Personally I wouldnt do it.
 

GarnetTy1473

Donating Member
Re: Diagnostic Mode

TYTILIDIE said:
I know htat the ECM goes into field test mode and it will run like crap. Why would you want to do that? Are you trying to read codes while you are driving? Personally I wouldnt do it.

You don't want to know why he's asking.
 

SyTyJedi

Jedi Council
Re: Diagnostic Mode

The ECM sends the following command out all ports/interfaces..."ALDL Racing"

/thread

;)
 

BigBadSmoosh

Picking fights on I-65 since 2013
Re: Diagnostic Mode

GM TURBO said:
We may have to get a few more ALDL Racing shirts printed up...

sign me up for one...

luckily i figured this out before making a pass down the track :oops:
 

MikeRenz

not stock
Re: Diagnostic Mode

I shoulda auctioned mine off at NATS this weekend. Prolly coulda bought some more raffle tickets that way :rotf:
 

MikeRenz

not stock
Re: Diagnostic Mode

Understanding the ALDL

This document covers most GM (General Motors) vehicles including the following:
GMC Chevrolet Buick Pontiac & Oldsmobile vehicles including: Astro, Typhoon, Syclone, S-10 truck, Blazer, S-10 Blazer; Camaro, Monte Carlo, Fiero, Firebird, Grand Am and other passenger class vehicles typically from 1983 to 1992 using OBD1 ECM (Engine Control Module).

The ALDL (Assembly Line Data Link) is located on the underside of the dash of your vehicle, just to the side of the steering column. It enables you to "pull codes" whenever your "CHECK ENGINE" light begins to flash. These codes alert you to certain engine components that are detecting a problem, such as, EST codes, low voltage to certain sensors, and high voltage to certain sensors (amongst many). To check codes and view data from the ALDL you can use a Scantool, Diacom, Datamaster, or other data viewing software, but all you really need is a paperclip. Pretty cheap, huh? Here's how to use the ALDL.

ALDL.jpg


Before we get into what the codes mean, let's learn how to get them. Using the above diagram, the ports are as follows:

A - Ground
B - Diagnostic Terminal
F - Torque Converter Clutch
G - Fuel Pump
H - Brake Sense Speed Input
M - Serial Data (Do Not Use)

To engage the TCC - jumper A & F - This will engage the transmission converter clutch. This is used by racers at the track to engage a mechanical link between the TC and the tranny, thus reducing slippage throughout the run. Has been found to provide better performance, but not recommended for daily use.
 

dgoodhue

BuSTeD 4.3
Re: Diagnostic Mode

Jimmy is asking for a different reason than more obvious 'ALDL Racing'.

The truck that blew the motor URSLO50 was running in ALDL mode, instead of locking the Torque Converter. Jimmy walked up to me aske me the correct pins for locking the converter, seconds after I had jumpered A-B pins [ALDL mode] in someone elses truck to check the IC Pump. I told Jimmy A-B as oppose to the correct A-F. I didn't even realize it until Jimmy reminded me much later in the night. Before Jimmy told, it didn't even register even after I had heard some mention about AB ->AE mistake.

On that run, the truck developed an apparent rod knock.
 

MikeRenz

not stock
Re: Diagnostic Mode

next year i think we should make sure we have the manuals handy. I know i drew a blank when the public was asked which ports for tc lockup - it has been a long ass time since i've needed to know :lol:

There has been a couple of 'he must be right' assumptions that haved cuased some trauma lately...i know i'll be double/triple checking myself when working on syty due to this
 

JSM

Active member
Re: Diagnostic Mode

Even funnier is Jimmy asked and I told him A-F but wasn't 100% sure.
 

bezerk

New member
Re: Diagnostic Mode

lol, he has his truck for 2 months no, never had a problem, comes to the nats with it, and somebody (good time member) ****ed it up? holy shit.
 

Jimmy

Banned
Re: Diagnostic Mode

bezerk said:
lol, he has his truck for 2 months no, never had a problem, comes to the nats with it, and somebody (good time member) ****ed it up? holy shit.
Yep.And they are going to pay for it.
 

GM TURBO

Sell Out
Re: Diagnostic Mode

I give the person who performed said act a lot of credit - he is doing what ANY standup person would do.
 

JSM

Active member
Re: Diagnostic Mode

bezerk said:
lol, he has his truck for 2 months no, never had a problem, comes to the nats with it, and somebody (good time member) ****ed it up? holy shit.

Were you there, part of the situation? Don't get involved.
 
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