Trouble codes - '89 Olds 88

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Old 02-28-03, 09:39 PM
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Trouble codes - '89 Olds 88

Hello again! Yes, it's the wife's Olds giving us fits again. As a refresher, it's an '89 model 88 Royale Brougham, 3.8l fuel injected v-6 and 4-speed automatic trans. Check engine light is on constantly, and reading codes gives 63, 64 and 65. My Haynes manual says they all mean EGR flow check for that engine. I had the EGR valve off to check for blockage, but found none. I cleaned off/out what carbon was present and replaced the gaskets, but still have the light. No, I haven't disconnected the battery to clear the codes; I don't want erase my wife's radio presets just yet.
The EGR valve is of the three-solenoid electric variety, and there is a 4-wire connector at the top of the assembly. I figure one hot wire for each solenoid and a common ground. Please correct me if this is wrong. Now, how does the ECU know whether the EGR valve/s is/are opening? Is there a sensor in the valve assembly, or is the O2 sensor responsible for this? Also, can I test the EGR valve for proper function with common tools, or even at all? Any insight will be greatly appreciated! Thanks - Chris
 
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Old 03-01-03, 03:34 AM
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Chris, take a look at these 2 links. You might want to print them out to read as they are several pages long. Those valves are not cheap so be sitting down when you call around for prices If necessary try www.gmpartsdirect.com for a better price on GM parts. You might need the part number off the old one for the correct replacement.

http://www.asashop.org/autoinc/dec97/egr.htm

http://www.wellsmfgcorp.com/counterp...erpoint3_4.pdf
 

Last edited by Stevo2; 03-01-03 at 03:51 AM.
  #3  
Old 03-01-03, 04:57 AM
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you have one common power wire the other 3 wires are grounded by the ecm to open the correct size solenoid i would check for key on power to the valve it is unusual to have all 3 codes for each solenoid, the ecm can usually detect if the egr is working by the o2 sensor readings.
 
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Old 03-01-03, 06:50 AM
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I agree with these guys. The valve is available through any parts store, no need to head to the dealer on this one.
 
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Old 03-01-03, 09:06 PM
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Thanks Stevo2, bejay and Joe-F. You've shed some light on this mysterious area for me. Just out of curiosity - with codes of 63, 64 and 65 at the same time, have I got one code each for each of the three EGR valve solenoids? The asashop link one of you mentioned was quite informative; the wellsmfgcorp one I never could connect to. I'm not going to give up on it yet, though.
Oh, I disconnected the battery this morning to clear codes and we've driven the car several times today. The check engine light has not even flashed, save for during the lamp test at start-up. There is still a slight intermittent miss at idle and when accelerating, but I suspect I need to look at spark plugs and air filter, too.
Thanks again for all the help. I'll post again when there is more to tell. - Chris
 
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Old 03-02-03, 03:08 AM
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Chris, the Wells link was really slow when I tried to pull it up. They may have a problem on there end. Clear the codes and see what comes up. Maybe they are just stacking up one after another due to a faulty valve?

CIRCUIT DESCRIPTION:

Codes 63, 64, and 65 are EGR flow test failures. The ECM on a closed throttle coast down will cycle the solenoids "ON" and "OFF" individually and look for a resulting change in engine rpm and O2 sensor activity.

NOTE: Because of all the possible color code combinations used on electrical wiring diagrams, always refer to ECM CONNECTOR IDENTIFICATION under ELECTRICAL AND ELECTRONIC WIRING DIAGRAMS for correct color code identification of circuit.



TEST DESCRIPTION: Numbers below refer to circled numbers on the diagnostic chart.

If a code is set, inspect the EGR for damage. Disconnect the 4 wire connector at EGR. Install a fused jumper from the battery to terminal "D" of the EGR. Start and idle engine, and with a jumper, ground terminals "A," "B," & "C" one at a time. You should be able to note a change in engine rpm as the terminal is grounded. Terminal "A" should result in a small change and "C" in a large change.

NOTES:

If the digital EGR valve shows signs of excessive heat, a melted condition, check the exhaust system for blockage or possibly a plugged converter. A plugged exhaust may be do to a:



STUCK OPEN INJECTOR
GROUNED DRIVER CKT
POSSIBLE FAULTY ECM
DIAGNOSTIC AIDS:

An intermittent may be caused by a poor connection, rubbed-through wire insulation, or a wire broken inside the insulation. Check for Poor Connection or Damaged Harness Inspect ECM harness connectors for backed out terminals "BC2," "BC3," and "BD2," improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection, and damaged harness.

Intermittent Test - If connections and harness check OK, connect a digital voltmeter from effected terminals to ground while moving related connectors and wiring harness. If the failure is induced, the voltage reading will change.
 
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