RoperC4

Im the guy with the 1993 ruby with the supercharger that has been through hell trying to have the performance my car is supposed to for a couple years only messing with it intermittently.

Anyways, I finally put my new ECM in yesterday, drove all day today and noticed several small issues not happening anymore (Tach guage not failing anymore, no burning out of the right bank only after starting)...

But my car still takes almost 15-20 turns to start and if left in heat the engine light comes on and the car struggles to run... Where do I turn next? What other information can I give to look in the next possible direction?

Am on my way outside to manually pull any stored codes... But my other question is, is that going to show me all the old codes that may have been on there before or no?

James93LT1

Has the car ever been tuned for the supercharger?

RoperC4

Yes.

James93LT1

Are you able to datalog your engine?

RoperC4

I found codes 28 and 34

RoperC4

If I am reading this right its saying map sensor low voltage... Is that sensor temperature sensitive? As in if its hot outside it starts failing? Because those are my symptoms...

jispr

I'd like to know where you got the ecm as I'm having "heat" issues also
that I think are tied to the ecm.
Jim

RoperC4

Will pm you the info when I get home was 250 shipped

RoperC4

So apprently the quad driver #3 is the code 28 which is the same code I have been posting about for over a year and the best advice here was get a new ECM. So I did that and still the same result...

Randy93

28 is a pain to diagnose, mine turned out to be a wire going to the a/c relay that had been nicked. But for some reason, fan relays go out quickly on 92-93 vette's, one of mine is out now and I replaced both about a year and a half ago.

34 I would say is a bad wire or connector or you got a defective ECM and I have heard of ECM's getting fixed and coming back w/new problems.

Also, don't let problems go, as I let my 28 go for a while and it took out my ECM.

RoperC4

if you were me where would you turn next? I know next to nothing about vehicle electronics, but am willing to spend a day with wiring, my fsm, and a buddy.

But I'm so tired of sitting at red lights and this stupid light pops on and then I struggle to get the car to drive accross the intersection.

I sold my motorcycle and rely on this car to work until I find me a beater truck...

RoperC4

On my way home from work tonight my TACH would also start malfunctioning for a minute or two as well as my SERVICE ASR light coming on simultaneously.

RoperC4

I found this old post on another forum whilst googling.



Lunatic Fringe
Jul 18 2009, 06:02 PM
GM vehicles. Quad driver fault; is the computer really the cure?

Probably not but, if the vehicle is early gm and has a constant check engine light with a quad driver fault code set the computer (ECM) may have became permanently damaged. So if the ECM is replaced without any diagnosis to locate and repair the cause of the fault then the new ECM may soon become permanently damaged as well. On newer vehicles with an ECM that has protected quad drivers replacing the ECM is most often not necessary.

There are many different code charts out with different code definitions. Some are quite vague while others seem over complicated. Some simply state, quad driver fault, while others will state, quad driver circuit fault, sense voltage low when should show high. Or sense voltage high when should show low. No mater how the description reads when a quad driver fault is set, then quad driver circuit testing is imperative before an ECM is replaced.

First let’s look at the ECM and its quad drivers. Most ECM controlled devices are either solenoids or relays. Typically, solenoids are used for a circuit when the current draw is 0.75 amps or less, and relays are used in a circuit when the normal current draw is expected to exceed 0.75 amps. GM uses quad driver circuits inside the ECM to control the outputs to these devices. So quad drivers (QD) are integrated circuits inside the ECM that it uses to close or open the circuit path to ground, turning the device on or off. Depending on the make and model year GM vehicles use different variations of quad drivers.
Quad drivers (QDR)
Are permanently damaged if a device or its circuit shorts, no added circuit protection.
Quad drivers II
Temporarily shut down and then reset if a device or its circuit shorts.
Quad driver modules (QDM)
Temporarily shut down, sets a fault code, and then resets if a device or its circuit shorts.

Lets look at testing quad driver devices and their circuits.

As we’ve all ready seen, most quad driver circuit faults are due to a short in a device or its circuit. (Wiring/connectors). However at times a device or circuit that is open will set a quad driver fault code.

Before replacing an ECM, always isolate the problem device or circuit. Replace the defective device or repair the circuit, and retest.

Each quad driver can control up to four devices. So diagrams will have to be used to find which devices the quad driver at fault is controlling.

Below is a typical diagram of QDM circuits. If this diagram was for quad driver B and that was the code that was set, we now know that this QDM controls, the TCC sol. Purge control sol. EGR control sol, and the check engine lamp.

A real diagram would list all circuit numbers, the wire colors, and connector terminal numbers. The important thing is that each device and circuit is tested, found to be good or repaired as necessary. The proper test on these circuits would be, with key off disconnect all ECM connectors, then with an amp meter set on the 10 amp scale connected to the control side of the circuit at the ECM connector and to ground turn the key on and check that the device turns on. With the device turned on, the meter should read 0.75 amps or less. Run this test for at least five minutes to make sure the device isn’t overheating and shorting. The TCC solenoid cannot be tested in this manner in a vehicle that has a normally open third gear switch inside the transmission. A scanner thru an extended road test best checks the TCC circuit.

A normally operating device and its circuit will have at least 20 ohms of resistance and can be checked with an ohmmeter. This will tell if the circuit or device is open however, this will not place the device in operation. So if the device is only failing due to heat after being in use for a period of time the fault will not be found with a resistance test.

With the proper test equipment it’s fairly easy to determine what circuit or device is causing a quad driver fault.

You will need a good digital multimeter and, if this first time buy the best would be one that has a 20 amp fused capability. The larger amp rating can come in handy when testing other electrical systems of your vehicle.
Also two 10 amp fused jumper wires keeping the in-line fuse as close to the power supply circuit as possible.

The most important thing to have on hand is information! The best would be the factory service manual but these are expensive.

Just because you have a Quad driver code doesn’t mean the Quad driver is bad. All a Quad driver code means is that an expected value is not present when it’s suppose to be. Also a Quad driver is a techy name for 4 on-off switches arranged in a group, hence the name Quad driver. The computer watches the voltage values on each switch and knows that if the switch is on, a voltage value will be seen. When the switch is off the opposite voltage value will be seen. Simply put, light on, light off. So what can set a quad driver code? You’d be surprised. How about a bad bulb? How about a bad fuse? The answer is yes to both questions. Yes, a bad bulb or failed fuse can set a Quad driver code. Start with checking your fuses. There can be up to 3 fuses that supply power to circuits controlled by the Quad drivers. If the fuses are good the next check would be of all or some of the following, depending on how your vehicle is equipped: Up shift light bulb, coolant hot bulb, shift to drive bulb, A/C relay, coolant fan relay, EGR solenoid, Canister Purge solenoid, even a speedometer output signal goes to one of the switches on the Quad driver. It’s more likely that the Quad driver code is present because the computer is not seeing the information that it expects to see at one of the switches.

Quad/Output Driver Module:
The Control Module in this vehicle controls most components with electronic switches which complete a ground circuit when turned on.

When the switches are arranged in groups of 4, they can independently control up to 4 outputs and are called Quad Drivers.

When the switches are arranged in groups of 7, they can independently control up to 7 outputs and are called Output Drivers.

Not all outputs are always used.


There you go. If you need help on how to convert the obd1.5 connector to a obd2 connector let me know.

http://bstuff.com/lofiversion/index.php?t62519.html



Where are the following items?

-EGR solenoid
-Canister purge
-A/c Relay

I was curious to check these because I read some other posts saying these little things caused everything that matched symptoms I have today.

Randy93

EGR is located on the back driver side of the intake, you can follow the egr hose and find it.
Evap is located on the front passenger side of the intake, it has 2 hoses connected to it, 1 goes into the throttle body and the other goes into a metal line behind the wheel well.

The A/C relay is built into the compressor.

Your 28 code is most likely a bad fan relay, but to check out which is pretty easy. Clear the codes and start the car and let it idle till the temp reaches 228 degrees, turn off the car and check for a 28 code, if not then start the car and turn the a/c on and then retest.

If it is the a/c relay, before replacing the compressor check for broken, nicked or bad connectors.

Your 34 code testing is a lot harder, you will need a multi meter and a test light.

Give me your email address and I will scan the procedures for you and email them.

RoperC4

I just want the car to stop dying at red lights and cutting out in hot weather...cutting out BAD.

James93LT1

You need to datalog you engine so you can isolate your problem down.

RoperC4

How? Will it still work with supercharger setup and/or could these supercharger components like the ignition box be shorting but the computer thinks it's something else?

toptechx6

After two years of problems you may want to think about taking it to a pro, forum vendor Corvettes of Dallas should be fairly close.

http://www.corvettesofdallas.com/

Ante up an hour or two labor and perhaps they can sort it out or at least give you an idea what is going on, good luck.

Corvettes of Dallas

We always treat our CF Members right. Give me a call and I promise we will be gentle.
Todd

RoperC4

I have talked to you a few times already Todd and yes you are very helpful, unfortunately until my pocketbook is able to support it plus the wife and 2 kids, I cannot just drop it to a shop... and still have money to buy the parts they will tell me I need.