I 'am a new forum member and from the island of Curacao N.A. I recently have bought a '93 vette. The car starts fine when it's cold. After a while driving the security light start flashing 3 times every 30 to 40 sec. If I switch off the engine it starts and immediately cut off. I have to wait until the it's cool before I can start the car again. If I take the car out the garage and put it in the sun (it can be pretty hot) 34 degrees celsius. it won't start either and does the same; start and cut off. It seems to be something with the temp but what?
It's very frustrating because you can't enjoy the car.
Pls help.
Huimphrey

 

I had that problem for about a year in my 1992. I just keep it cool by parking under trees, etc etc.

One day my starter crapped out so I replaced that. I had an extra ECM I purchased on Ebay so I decided to installed that too. After that I no longer had the "hard to start when hot" syndrum.
I assume the problem was one of those componets.

PS Welcome and Congrats. Have fun fighting off all the chicks.

 

Does the tach start jumping wildly just before it dies? Does it just crank but acts like there is no spark occuring when you restart a hot system?

Could be a number of things:

Ignition Coil Module
Tach Filter
ECM
Coil

in this order.

 

I checked but the tach does'nt jump around. The engine runs for a couple of seconds and than cut off. What about the flashing security light during driving. I have noticed too that if I turn the key but don't proceed to start, the security light start flashing too. Is that normal. I'am going to check the other stuff out.

Thanks
Humphrey

 

Thanks I will check some other suggestion that I received out. If none ofg themm give the right result I will have to order a ECM.
I'am glad to be a Corvette forum member.
Regards

 

I'm not doubting but I have to ask for verification, are you sure it's the Security lamp flashing or is it SYSTEM lamp flashing?

Security lamp flashing usually is an indication to the driver to arm the UTD (universal theft deterent) system. If your system is armed and you approach with the transmitter it unlocks the doors, you should see a flashing Security lamp when you open either door or the hatch. There are other combinations but they can mean things like door only mode or you manually lock the door with the lever not the key.

If it's SYSTEM then that is telling you there is a problem. You need to pull the codes. Have you done that yet? Are you familiar with pulling codes?

Before you start throwing parts at it, let's verify DTCs (Diagnostic Trouble Codes).

I don't suspect the Tach Filter if its not jumping wildly just before it dies. You could have a condition causing the FEDS to be enabled which shuts off fuel.

Let us know, we can help with a little more info.

 

It's ok asking all the question you need to help me fix this. Ok when driving ,the security lamp and the system sign start flashing at the same time and same pace. I will pull the codes this evening.
Thanks
Humphrey

 

Kewl, yeah you have some DTC's set.

Curious, where exactly is Curacao N.A.

 

Curacao is a small Island appr. 60 miles of the caost of Venezuela. It's also the native Island of Andruw HJones of the Atlanta Braves and the last year Little league World Champions and this year second place. I used a friend DTC its the "Domestic pathfinder 95". He is not right now so I still playing around with it. But I got code 28. That doesn't make much sense for me. Pls advice

 

Kewl I wondered where it was.

On the codes and the code puller you can do this yourself without any external device as your 93 has that ability. I put in a request to get a copy of the complete list of all codes and the pins to jump for you. It was posted but some how got pulled down. I should have it this evening when I get home from work.

Basically locate the DLC connector just below the steering column and driver's knee pad. It has a plastic cover over it. Pull it off and using a large paper clip bend it in a U shape and with the key off insert the ends into pins A & G and A & B.

With A & G jumped turn the key to On and the display will change to DTC mode. It will automatically cycle through all three test modes 1.1 for CCM codes, 4.1 for ECM/ETBCM codes, and 9.1 for ABS/ASR codes. If no codes are found you will see a 12. A "C" in front of a code means its current and happening, an "H" in front is historical meaning something happened and set the code since you cycled the ignition.

I can only guess at what your 28 is.

When you jump A & B and turn the ignition on the Service Engine Soon lamp on the DIC panel will flash the number of the code three times then move to the next one. For example at DTC 12 (no codes) would be flash.... flash flash three times, a DTC 34 would be flash flash flash .... flash flash flash flash, three times. When it returns back to a 12 to or that is all you get its either done displaying codes or if that is all you get then that means you have no ECM codes.

I can go into details on controlling functions from the CCM display but want to ensure you are up to speed first on this.

Here's a couple pictures to help.

 

Here's a link to the PDF on pulling and interpreting DTCs.

Compliments of Bogus.

DTC's and how to read them

 

I've been away a couple of days, but I'am back. I checked code 28 in Chilton corvette manual and it says something about Quad driver module #2 circuit or transaxle gear switch, probably 3rd gear switch. Do you have an idea what this means??. I cleared the code but as soon as I start the car it comes back.

Regards, Humphrey

 

Well right off the bat diagnostics say trun a Tech 1 on the Misc Test. So that part needs a dealer or shop w/Tech 1.

All the focus seems to be around the fan relays as this is the test portion of Misc Test. Also, possible faulty ECM connection, faulty ECM, AC relay. and relay solenoid valve/connection.

Let me look some more.

 

Sorry had to finish watching SmallVille. "He finally flew"

Essentially the first phase of the Tech 1 misc test is to activate the fan relays first fan 1 then fan 2. If one follows the flow and assumes fan 1 and fan 2 both activate, then the next question is does the AC relay operate.

If it does perform this test:

Key Off
Disconnect ECM Connector B
Key On
Using a DVM on 2 amp scale, measure the current from harness terminals B4, B5 B10 each to ground. Each terminal should measure .75 amps but not 0.

If they do then a Tech 1 is needed to monitor the QDM status while idling. Check for bent pins on the ECM connector. If the DTC 28 reoccurs, replace the ECM.

If it does not meansure the currect current, AND if any of the above relays don't activate when they were suppose to above then perform this test. (I combined the two results here since it is the same flow chart test. By doing so the 'AND' above is to separate two entirely different things and the measuring of current is not related to my including the relays not activating. As I have already given the 'if the current measure is correct' above.

Ignition Off
Disconnected affected relay connector i.e., fan 1 relay, fan 2 relay, AC relay.
Connect a test light between relay coil connector terminals.
Ignition On
Ground diagnostic test terminal.
Testl ight should be ON is it?

If yes the connect the test light from ignition feed circuit of the relay solenoid valve to ground.
Test light should be On.
Is It? If it is, you have a faulty ECM, ECM connector or open relay/solenoid valve driver circuit. If no, then you have an open relay/solenoid valve ignition feed circuit.

From above testing the relay coil connectors and ground if the test light is On then unground the test terminal light should be Off is it? If so, the its a faulty relay/solenoid valve connection or faulty relay/solenoid valve. If it doesn't light then disconnect ECM connector B is the light On now? No faulty ECM, yes you have a grounded relay/solenoid valve driver circuit.

All in all its point to an open or short in the circuits. If that isn't the case then its most likely either the ECM or relay/solenoid valve.

Hope this helps.

 

Not sure this is your problem but last quad driver fault I saw here was a bad ecm.Make sure to exhaust all the other options first.If you do not have one get a Factory service manual from Helm you can order it online.Try doing an archive search on quad driver.

 

Thanks for the pictures and the site you sent me. The code 28 was related to the fan because the relay was grounded so the fan was always on. I removed the ground and cleared the code. I used the scannner and checked if there were other codes. I then started the car. After appr. 15 minutes I lost contact with the EMC. I used the "paperclip methode" works very good, .The moment I turn the ignition key I got C41,H41 and H54 codes. Code 41 is ECM data comm. lost H 54 is Fuel enable error. A couple of minutes after getting the codes the security and the sys light started to flash. I could not clear the codes. After 5 hours I could start the car again without any problem. I seems to be temp problem. I found some modes in which the fuel is cut of temporaly: decelaration,overspeed,converter overheat, power/torque management. Do you know some more that can be temperature related. What about the coolant sensor or the oil temperature sensor. I want to exhaust all other possibilities before thinking of a defective ECM.

Regards Humphrey

 

From the sounds of it, I'd replace the ECM. The codes your getting, (FYI the FEDS was the results of a code), the heat related issue. These all point to the ECM. You should be able to talk to the CCM though and clear codes that is interesting. Also disconnect the battery for a few minutes that will clear them.

It's not that expensive and considering the age, and of course knowing first hand after what I went through with mine.

I think it was like 207. plus a core chg of 112. But that was credited back when I returned the old one.

It takes about 15 minutes to swap it. Three nuts and post, disconnect the harness connectors. Remove the access cover and pop out the PROM move it to the new one secure the access cover. Transfer the studs, attach the harness secure the ECM.

Start er up.

 

I've been following this thread and getting an education.
Just so I'll know, I assume the battery is disconnected before disconnecting any electrical parts?

 

Oh you mean the part about how easy it is to replace the ECM? That I didn't mention disconnect battery. Yes your right, besides I think Bogus calls me the disconnect king or something like that. I disconnect the battery for daym near everything LOL. I was just trying to make a point of how easy it is.

Sorry

 

I think that after all My vette has the "hard to start when hot "syndrum too. I didn't want to think about that because it's going to take at least a week to order one from the States.
I still didn't have the time to drive aroiund too much

Regards
Humphrey