Intermittent Code 61 Ideas
 

Hi there GC needs a little help. I getting an intermittent SES light that wont hard set but always leads back to a code 61 (Secondary port throttle system error). Would a bad or non working vacuum pump cause this issue? It happens the most of the time when the Cruise control is set and the car has to pickup speed in 6th gear. As the car has to accelerate the SES light will illuminate and when the car levels off in terrain the light goes away. Im reading the troubleshooting section of the FSM and it appears when the Vacuum secondary actuators lose pressure that the ECM commands the air pump to kick in to compensate.

From what im reading either one of these actuators are suspect, as is a check valve, Air pump, secondary port actuator and the tubing. Asking if anybody else outthere has seen this repeat symptom. Is there a check for just the vaccum pump. I dont know if it ever comes on as my fans race on almost immediately in my car due to the prom setting. Just looking for ideas and any been there's and done thats. out there Thanks Daryll :happy1:

Re: Intermittent Code 61 Ideas
 

darrell, 2 things have you tried having someone turn the ignition on but not to start with you out by the vac pump .if it working it should go on for a very short period and then shut off. and 2 you can override the prom setting by taking your valet key and turning it off. then go put it in cruize control on the freeway and see what happens that will narrow it down for you . oh yeah there is also a fuse for the vacpump on the inside of the drivers wheel well . ck the service manual just to be sure . the fuse was out on my 92 when i first got it .dont know why it blew but replaced it and never had another problem . hope this helps

Re: Intermittent Code 61 Ideas
 

also the corvette action center has a really good and quick troubleshooting guide in the zr1 section

Re: Intermittent Code 61 Ideas
 

Daryl, I know you don't want to hear this but an intermittent 61 usually is vacuum related....usually. Figure the control solenoid is an on - off switch, so electrically it has to set a hard code if that side of it fails. If the vacuum side has a soft failure, like crap in it, then the 61 becomes intermittent. Likewise if the pull off canisters have soft failure in the rubbers, then maybe an intermittent 61 happens. Oh, also the second MAP sensor under the ECM where the ECM monitors the level of vacuum during secondary operation...that could also be the source of a 61, or any of the vacuum hose connected to any of the stuff under the plenum for the secondary system....which then goes back to the pump & any issues it could have.

JMHO
Tom:o

:cheers:

Re: Intermittent Code 61 Ideas
 

Tom there is a seconary MAP sensoner under the ECM? I had no idea I thought there was only one behind the plenum. Is that on the underside of the ECM bracket?

Re: Intermittent Code 61 Ideas
 

Agreed

Re: Intermittent Code 61 Ideas
 

GC, I am not sure if the Code 61 is related but here is what I observed on a 1994.

There is a pressure switch that monitors Secondary Vacuum and turns OFF the Secondaries if they have been commanded ON and the Secondary Vacuum drops too low to hold the secondaries open.

During acceleration, the Secondary system would cycle on and off. I had a scanner connected to the car during operation. What was happening was that a bad check valve between the secondaries and the other vacuum uses allowed vacuum "loss" when manifold air pressure went up (throttle valves wide open). The secondary vacuum pressure switch would sense rising pressure (loss of vacuum) and would shut off the secondaries. I believe that a code occurs from that event.

Jim

Re: Intermittent Code 61 Ideas
 

So that's what that is. I saw that under the ECM on my '90 ZR-1, looks the same as the primary MAP sensor (minus the silver bracket). Was wondering why there was a second one. Good info, thanks Tom!


Here is a picture of the one on my Z:

http://i13.photobucket.com/albums/a2...STA70076-1.jpg

Re: Intermittent Code 61 Ideas
 

Jim I think that is certainly possible. I need to set aside the time to trouble shoot all these areas. I have a new Pump, one new silver metal actuator that works and a new Secondary throttle black plastic actuator. Now I know why a lot of folks are eliminating this system and pinning back the secondaries

Re: Intermittent Code 61 Ideas
 

When your on the throttle does it shut down at 3k?
If so check your power switch make sure it works/stays on.
Put a scanner on the car check the volts on secondary MAP it needs to be below 3.6 volts.
Otherwise you have a vacuum leak search and find leak,also check vacuum actuators put vacuum to them make sure they open by 7" of vacuum and stay open,they don't usually go bad but if your in there might as well check them.

Just a thought you sure you plugged in the electric plug to the vacuum solenoid. Done that once:)
Since then i yanked the secondaries.

Pete