E027 Code, A/C Problem and Service Ride Control

Antiqueairways · #1 (**permalink**) 10-10-09, 09:51 PM

I just bought an old 92 STS (an oldie but a goodie) The service engine soon light is on. I pulled the codes and the primary one seems to be the E027 code which I believe indicates "open throttle signal switch." Where is the switch located and how can I trouble shoot it?

The A/C is not working either. I tried to hook up my gauges, but the high side test port doesn't seem to have the typical schrader valve in it and consequently, I can't get a high side reading. The compressor runs, but does not cool. Any ideas on the test port or possible ideas on it not cooling? I'm considering converting it to 134A.

The info center also displays "Service Ride Control." From the online research I've done, it may be the control module that is gone kaflooky. It also seems they may no longer be available, but there is a wiring harness available to bypass the system. Any comments on this issue or the idea of bypassing the system?

Thanks in advance for any help I get.

**Ranger** · #2 (**permalink**) 10-10-09, 10:15 PM

I think it is on the throttle linkage or the ISC motor. Just try cleaning the contacts.

Is the A/C service port a quick disconnect type? If so, then it has already been converted.

Antiqueairways · #3 (**permalink**) 10-10-09, 10:47 PM

I'll have a look in the vicinity of the ICS motor in the morning.

I had thoughts that the vehicle had bee converted too, but the low pressure side does not have the converted fittings and the high pressure side doesn't look like I think it should if it were converted. I may have to send you a picture for a second opinion.

Thanks Again.

**Ranger** · #4 (**permalink**) 10-10-09, 10:52 PM

Well, the R12 fittings are threaded much like a tire valve. The R134a fitting is very similar to an air compressor hose (Male end).

Antiqueairways · #5 (**permalink**) 10-11-09, 09:41 PM

Ok... well, I still don't know why the high pressure fitting isn't like any I'm familiar with. Maybe Cadillac had some proprietary fitting for some reason. Regardless, I decided the compressor was bad. I replaced it, the accumulator/dryer and the orifice screen, vacuumed the system and refilled it with R134A and I have good cold air. I still have no way to check the pressure on the high side, but as long as it's cooling, what can I say.

I cleared all the codes on the computer and no new codes have shown up except the service ride control message. I haven't driven the vehicle far enough to see if anything else shows up, but so far so good. I'd still like some guidance on the ride control issue and the idea of by passing the module.

Thanks again!

**Ranger** · #6 (**permalink**) 10-11-09, 10:31 PM

Sounds like that car was worked on and someone used whatever they had on hand.

Antiqueairways · #7 (**permalink**) 10-18-09, 12:47 PM

Ok.... Info for the group.... Since no one for sure could tell me about the throttle signal switch or where it is located, I found a source that knew, so I'm here to share. The switch in question is part of the idle speed control motor which has 4 wires leading to it. The throttle position switch is on the opposite side of the throttle body and has 3 wires leading to it. The problem that was setting up the E027 code was one of the wires going to the idle speed control motor wasn't making contact. This was because the plastic plug was disintegrating from old age. I "engineered" a temporary fix to hold the wires in place till I hopefully can obtain a replacement plug from the dealer. The motor seems to stay in the fully retracted state all the time now, but the engine idles fine regardless and in driving the car there seems to be no idle issues. The code cleared and stayed clear.

**Ranger** · #8 (**permalink**) 10-18-09, 01:14 PM

I think what you may be talking about is the open throttle switch or maybe it's called the closed throttle switch, not sure.

Antiqueairways · #9 (**permalink**) 10-18-09, 01:52 PM

Im absolutely sure what I'm talking about now. The throttle signal switch is contained inside the idle speed control. It and the PCM controls the position of the plunger on the control. No one in this group knew where the throttle signal switch was, but I do and now so should everyone else.

submariner409 · #10 (**permalink**) 10-18-09, 02:08 PM

Antique, Your STS runs a 4.9, right ?? So it has a throttlebody with 2 injectors on top of the engine ??

............for my own brain file.............

Antiqueairways · #11 (**permalink**) 10-18-09, 02:24 PM

Yes, this is a 4.9L with the throttle body and 2 fuel injector rails along each side of the intake

Antiqueairways · #12 (**permalink**) 10-18-09, 02:55 PM

PS... I just found the connector and wiring to replace the rotten one to the ISC on Ebay for $5.55 :-)

**Ranger** · #13 (**permalink**) 10-18-09, 05:21 PM

Quote:

Originally Posted by submariner409

Antique, Your STS runs a 4.9, right ?? So it has a throttlebody with 2 injectors on top of the engine ??

............for my own brain file.............

No Sub, the 4.9 is multiport injected, not TB injected.