Forum Discussion

udidwht's avatar
udidwht
Explorer
Jul 06, 2018

DTC codes

Been driving the 1994 Fleetwood Southwind Storm (454 TBI w/4L80E) to/from work (18 miles each way) and upon parking today I was greeted with the 'Service Engine Soon' lamp. Engine is and has been running great. Idles fine.

I did take some time this past summer (2017) and cleaned all the battery posts and engine chassis ground strap (both ends). Applied some dielectric grease to them as well.

I jumped the jumpers and the codes showing are:

35
68
71

I had these exact same codes back in late July-Aug 2017 odometer then 53,XXX miles. I then (Aug 2017) replaced the IAC valve (old measured 10mm pintle) and the Idle speed control actuator.

(following thread for those details)

https://www.chevytalk.org/fusionbb/showtopic.php?tid/346482/post/2706359/hl//fromsearch/1/#2706359


I have not had the SES light since the previous 2017 episode. I'm now approaching 57,XXX miles. On my last trip I took the time to remove and thoroughly clean the battery grounds & posts as well as the engine - chassis ground strap (both ends). According to another forum member (someotherguy) stated he could not find code 71 for 94 P30 454TBI but stated it does reference to 1994 diesel variant with regards to cruise control.

I also made checks then for vac leaks. None found. Used carb spray small shots all around TBI base gasket and throttle shaft (both ends. Engine very nice.

I had the shift solenoids (A & B) replaced in ~ late Sept 2017, wiring harness and force valve turned up 1/2 turn the only codes that showed were 68 and 87. Jerry Clutch & Trans Grants Pass. Or. used his diagnostic computer to pull them. Odometer was ~ 55,XXX when work was done. This was on the return leg from Huntington Beach, Ca. to Seattle, Wa.

Some items I've replaced since purchasing RV:

1. TPS sensor - Delco 2016
2. O2 sensor - Delco 2016
3. MAP sensor - Delco 2016
4. Radiator cap - Delco 2016
5. IAC valve 10mm petal(Enchlin NAPA) 2017
6. Idle speed control actuator - Delco 2016
7. Shift solenoids A & B, wiring harness, force valve turned up 1/2 turn (4L80E) Jerry's Clutch & Trans Grants Pass, Or. (Sept 2017)
8. Full tune up - wires NAPA Belden Edge, plugs (Autolite). cap & rotor - Delco, Heat shield sleeve covers for wires (Sept 2014)
9. Purge valve - Delco (06 2018)
10. EGR gasket replaced (EGR cleaned reinstalled)
11. Brakes - Front rotor hub assemblies, Centric pads, Master cylinder
12. Front & Rear trans speed sensors (NAPA Enchlin) Aug. 2017
13. PCV valve - AC Delco 2016
14. Fuel filter - WIX Sept 2014
15. Upper & lower radiator hoses, By-pass hose, new 195F T-stat AC Delco (06-2018)
16. New ignition switch (AC Delco)

1994 Fleetwood Southwind Storm
P-30 chassis 7.4L 454 TBI 56,4XX miles and counting....
VIN# 1GBJP37N4R3314754
Class A
  • udidwht's avatar
    udidwht
    Explorer
    Jul 06, 2018
    rgatijnet1 wrote:
    Maybe this will help: OBDI codes


    Thanks but I had someone tell me that some codes may or may not be for my chassis. For instance code 68 is trans slip but on your link it shows as:

    Code 68 A/C clutch relay circuit error (shorted to ground)

    I know this as it was a code that threw when I had the trans serviced for the shift solenoids, wire harness and force valve turned up.

    As for code 35 I do believe it relates to the IAC. I replaced both the IAC and the Idle speed control actuator when I originally had the code 35 appear ~ 1 year or so ago. Have not had that code or SES light since then. Back when it happened the first time it flashed the same 3 codes 35, 68 and 71.

    I had another person tell me he was not able to reference (service manuals) a code 71 for my chassis but it did show for the 1994 diesel relating to cruise control item.
  • Gjac's avatar
    Gjac
    Explorer III
    Jul 07, 2018
    udidwht wrote:
    rgatijnet1 wrote:
    Maybe this will help: OBDI codes


    Thanks but I had someone tell me that some codes may or may not be for my chassis. For instance code 68 is trans slip but on your link it shows as:

    Code 68 A/C clutch relay circuit error (shorted to ground)

    I know this as it was a code that threw when I had the trans serviced for the shift solenoids, wire harness and force valve turned up.

    As for code 35 I do believe it relates to the IAC. I replaced both the IAC and the Idle speed control actuator when I originally had the code 35 appear ~ 1 year or so ago. Have not had that code or SES light since then. Back when it happened the first time it flashed the same 3 codes 35, 68 and 71.

    I had another person tell me he was not able to reference (service manuals) a code 71 for my chassis but it did show for the 1994 diesel relating to cruise control item.
    The problem with these generic codes is that they are very unreliable in troubleshooting engines with an OBD 1 system, you can find may conflicting ones on the internet. There are no code readers like OBD2 and OBD1 codes are specific to individual ECU's. There was a guy on here years ago that had a program on his laptop that connected with a VGA cable that had the same ECU as me that was very helpful in diagnosing these codes.
  • udidwht's avatar
    udidwht
    Explorer
    Jul 07, 2018
    Update:

    I had also purchased a new ignition switch awhile back (AC Delco) and decided to install it today. I was going over some wire diagrams for P30 chassis and noted the switch seems to serve as a path for the ECM and other items as well.

    Finished replacing the ignition switch and noted that the orange wire was clearly not into the plug far enough took very little effort to remove the wire itself from the connector prior to even removing the connector from the switch. After haven removed the switch the switch itself does not show any signs of getting to hot on any connector/s. It was dated Dec 1993.

    New one is now installed and wire spades were coated with some SuperLube dielectric grease. Made certain the wires were connected and seated well onto the spades. ECM was reset (battery cable removed during switch replacement). Grounds were clean and lightly coated with dielectric grease as well.

    Will monitor for issue/s.
  • wa8yxm's avatar
    wa8yxm
    Explorer III
    Jul 07, 2018
    I recall a 3x code on my car MAP sensor.. Took me like 1 minute to fix once I knew it was Emissions related (Re-connected sensor tube). That would have been 33 or 34

    These are GM codes

    Code 35 IAC problem or idle error

    Code 68 A/C clutch relay circuit error (shorted to ground)

    Code 71 A/C evaporator temp sensor circuit error (low temp indicated)

    I do not know the IAC so can not help you with that

    68 I would inspect all wiring to the A/C clutch
    71 Suggests the Evaporator is icing up.. May be related to the 68
  • udidwht's avatar
    udidwht
    Explorer
    Jul 08, 2018
    Ive confirmed that 68 is Trans lip on this rig. But 71 appears related to a 94 diesel cruise control item.

    35 is related to the IAC but I replaced both the IAC and the idle speed control actuator last year. I have checked for vac leaks. None found and engine idles nicely with no issues. The air conditioner works nice as well.

    As for the trans code it also showed during my return trip home when I had Jerrys Clutch & Trans in Grants Pass, Or. resolve my limp mode. Both shift solenoids were replaced along with a new internal wire harness and he turned the force actuator up 1/2 turn. The codes pulled then were:

    68 Trans slip
    87 Shift solenoid A

    I did replace my ignition switch the other day. While looking over the old one I found the orange wire was not seated all the way into the connector. When I grabbed it, it came out easily with close to no effort.

    So the new switch is in and wires are all connected well. Seems to have had a positive effect on what I originnaly believe was a wonky temp gauge sensor. There were times when the dash gauge would read higher than I knew the engine was while trending with my IR temp gun.

    For instance....IR gun would show 195-205 at T-stat housing yet dash gauge would show 230-240. I know the dash gauge is far from perfect and its normal to have it go to 220-230+ after a highway run or grade pull then exiting the highway (heat-soak). But that wasn't the case with mine. It would do this after just driving around town with little load on the engine. T-stat housing IR readings were normal 195-205F. Lower hose would range anywhere from 30-50+ degrees lower on average.

    Now that I have replaced the ignition switch that seems to only happen after exiting a highway run but recovers after a bit. The temp sensor works off resistance measurement any added resistance via wonky wire connection can effect their accuracy.

    During highway runs the dash temp needle would hover between half a dash needle width left of 210F to half a needle or so right of 210. I'm running a stock 195F T-stat (AC Delco). I just replaced all my hoses and installed a new t-stat Delco about 3-4 weeks ago.

    Also used 2 cans of condenser coil cleaner on the AC condenser and radiator. Nice and clean now.
  • rgatijnet1's avatar
    rgatijnet1
    Explorer III
    Jul 08, 2018
    udidwht wrote:
    Ive confirmed that 68 is Trans lip on this rig. But 71 appears related to a 94 diesel cruise control item.

    35 is related to the IAC but I replaced both the IAC and the idle speed control actuator last year. I have checked for vac leaks. None found and engine idles nicely with no issues. The air conditioner works nice as well.

    As for the trans code it also showed during my return trip home when I had Jerrys Clutch & Trans in Grants Pass, Or. resolve my limp mode. Both shift solenoids were replaced along with a new internal wire harness and he turned the force actuator up 1/2 turn. The codes pulled then were:

    68 Trans slip
    87 Shift solenoid A

    I did replace my ignition switch the other day. While looking over the old one I found the orange wire was not seated all the way into the connector. When I grabbed it, it came out easily with close to no effort.

    So the new switch is in and wires are all connected well. Seems to have had a positive effect on what I originnaly believe was a wonky temp gauge sensor. There were times when the dash gauge were read higher than I knew the engine was while trending with my IR gun.

    For instance....IR would show 195-205 at T-stat housing yet dash gauge would show230-240. I know the das gauge is far from perfect and its normal to have it go to 220-230; after a highway run or grade pull then exiting the highway. But that wasnt the case with mine. It would do this after just driving around town with little load on the engine.

    Now that I have the switch in that seems to only happen after a highway run but recovers after a bit. The sensors work off resistance measurement any added via wonky wire connection can effect their readings.

    During highway runs the temp hovers between 210 to half a needle to the right of 210. Im running a stock 195f T-stat. I just replaced all my hose and installed a new t-stat Delco about 3-4; weeks ago.


    With the age of your coach, I would suggest a thorough flush of the exterior of the radiator. Unless this has been done frequently in the past, road debris, dirt, corrosion can form between the fins and decrease the cooling capacity of your radiator.
  • udidwht's avatar
    udidwht
    Explorer
    Jul 09, 2018
    rgatijnet1 wrote:
    udidwht wrote:
    Ive confirmed that 68 is Trans lip on this rig. But 71 appears related to a 94 diesel cruise control item.

    35 is related to the IAC but I replaced both the IAC and the idle speed control actuator last year. I have checked for vac leaks. None found and engine idles nicely with no issues. The air conditioner works nice as well.

    As for the trans code it also showed during my return trip home when I had Jerrys Clutch & Trans in Grants Pass, Or. resolve my limp mode. Both shift solenoids were replaced along with a new internal wire harness and he turned the force actuator up 1/2 turn. The codes pulled then were:

    68 Trans slip
    87 Shift solenoid A

    I did replace my ignition switch the other day. While looking over the old one I found the orange wire was not seated all the way into the connector. When I grabbed it, it came out easily with close to no effort.

    So the new switch is in and wires are all connected well. Seems to have had a positive effect on what I originally believe was a wonky temp gauge sensor. There were times when the dash gauge were read higher than I knew the engine was while trending with my IR gun.

    For instance....IR would show 195-205 at T-stat housing yet dash gauge would show230-240. I know the dash gauge is far from perfect and its normal to have it go to 220-230; after a highway run or grade pull then exiting the highway. But that wasn't the case with mine. It would do this after just driving around town with little load on the engine.

    Now that I have the switch in that seems to only happen after a highway run but recovers after a bit. The sensors work off resistance measurement any added via wonky wire connection can effect their readings.

    During highway runs the temp hovers between 210 to half a needle to the right of 210. Im running a stock 195f T-stat. I just replaced all my hoses and installed a new t-stat Delco about 3-4; weeks ago.


    With the age of your coach, I would suggest a thorough flush of the exterior of the radiator. Unless this has been done frequently in the past, road debris, dirt, corrosion can form between the fins and decrease the cooling capacity of your radiator.


    I used 2 cans of condenser coil cleaner on the A/C condenser and radiator. Both are nice and clean. Nothing IR gun reading wise leads me to believe it's related to radiator given readings are normal.

    Just drove from Seattle to Lynden, Wa. and the dash readings during the drive (flats) ranged from a half needle width to the left of 210 (middle) to 1/2 needle width to the right of 210 or so. After the highway run (exiting) it would creep up to ~ 220 (heat-soak ) but hold then recover after a bit of town driving.

    The recovery bottle shows no signs of overheating. such as very full of overflowing. After that drive it was half way or so between 'Full cold and Full hot'. Once the RV was stone cold the recovery bottle was right on 'Full cold mark'.

    I replaced the A/C aux fan motor a month or so ago after noticing the old motor was was not working. It's works great now. The fan according to service manual (1994) is designed to come on at approximately 221F degrees. The sensor for it is located in the passenger side cylinder head.

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