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1989 Shelby CSX
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Discussion Starter #1
I am working on a ‘89 CSX and I’ve gone through the engine, sensors and electrical. It’s running well and only has one code left on it. It is giving me a code 36- Turbo IV #3 cent solenoid open/short. From what I’m reading, this code is for the wastegate on the non-VNT, so is this the solenoid that controls the turbo vanes? From how the boost gauge is reacting giving the engine revs, it appears to be building boost quickly and can hit full boost at 5k rpm. What should I be looking at to fix the problem causing his code? I haven’t been able to run the car very much yet, so I was curious if some highway pulls would clear up anything stuck in the turbo.
 

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I am going to assume that the 89 CSX is the same as my 90 VNT.
I do not know exactly what the symptoms are for loss of VNT Solenoid #3, I have yet to experience any issues with the VNT Solenoids. (KNOCK ON WOOD!!!)
You should be able to hit full boost in 2.3 seconds from a standing start and full boost should hold at WOT.
Here are Chryslers diagnostics for Fault "VNT Solenoid #3 CKT."
IMG_NEW.jpg IMG_0001_NEW.jpg
 

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1989 Shelby CSX
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Discussion Starter #3
Awesome, your diagram tells me which one to look at without having to test all 3! Through a few pages of google searches, I found that it is a Mopar vacuum solenoid, part# 5234217. I found a new one on ebay so I’ll have a spare when I go through the testing of it. At least it’s in an easily accessible place compared to the vacuum diagram on the turbo itself.

I can tell you it isn’t building boost that quickly so this may be the culprit.
 

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In 30 years of owning my VNT I can say I only once had a lack of boost problem and that was when the charge pipe from the intercooler to the TB blew off at the track.
Usually my issues are the opposite...Overboost!!! Sucks when your OE Muffler falls apart, how do you fix that...Stop Racing.
Head Gasket (A) 5-21-10.JPG

Part #5234217 is a "Universal Solenoid", it is the replacement for two of the three VNT Solenoids and the Baro Solenoid and is still readily available, always nice to have a spare.
Chrysler Universal Vacuum Solenoid 5234217.jpg VNT Solenoids 1.JPG

In the future you do not need to do a google search for part #'s, we have the entire Chrysler Parts Catalog on site.
You can locate possible sellers using...https://www.rearcounter.com/

CHRYSLER PARTS CATALOG
 

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1989 Shelby CSX
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Discussion Starter #5
Thanks for all the information with the diagrams and parts list! Your photo is extremely helpful as well. The Baro Solenoid you mention, is that the VNT Solenoid #1 since its different from the other two?
 

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The Baro Solenoid is located next to the Map Sensor.
VNT solenoid #1 is located on the strut tower and does not look like the other Solenoids.
The Universal Solenoid is the same as VNT 2, VNT 3 and the Baro Solenoid.
Although it looks the same the Universal Solenoid is not a replacement for the Purge Solenoid which is also located with the VNT Solenoids.
 

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1989 Shelby CSX
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Discussion Starter #7
Well glad to verify that the ‘89 setup matches the ‘90 setup and diagrams. At least I know which one is causing the CEL so I can check it with voltage this weekend and see if it actuates.
8C0D8931-7FFC-4E50-AD68-924AE3651D5A.jpeg
 

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1989 Shelby CSX
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Discussion Starter #9
I just wish there was more room between the firewall and the O2 sensor! Getting the old one out was a challenge.
 

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Question...
Can you post a pic of the relays on the driver's side of the vehicle.
I am currently helping another member that has an 89 CSX and he says his vehicle has the 88 relay setup, Starter, Cooling Fan, A/C Clutch, ASD.
 

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1989 Shelby CSX
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Discussion Starter #11
That’s me too, sorry for the confusion. Have two threads going for two separate issues with the same CSX.
 

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Discussion Starter #13 (Edited by Moderator)
Ok, I think I’m at a bit of an impasse and could use some guidance. Replaced VNT solenoid 3 and still the same code. New solenoid measured at 30.1 ohms. Following the troubleshooting guide supplied earlier;

1. VNT 3 solenoid connector was fine
2. Voltage at VNT 3 solenoid - 13V
3. Pin 36 at engine controller checked out fine.
4. Voltage at Pin 36 while disconnected from engine controller, with key on and using battery to close circuit - 11.62V.

Now the next step is to replace the engine controller. For fun, I measured the wire between Pin 36 and the VNT solenoid 3 connector and got 1.6ohm which is below the 5 ohms required. So which is it, a bad engine controller or a bad wire to the solenoid?
 

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On the ground side control (Cavity 36) they want to be sure you are not shorted to ground.
Both the SBEC and Solenoid should be disconnected when performing this step.
With the ohmmeter black lead connected to ground probe cavity #36 of the SBEC connector with the red lead.
(Take caution not to push your probe into the terminal or it may spread/damage the terminal.)
Since the wire from the Solenoid to SBEC is no longer connected to anything there should not be any continuity to ground, the meter should read Open/Infinite.
If you are getting a resistance reading other than open/infinite (or above 5 ohms as Chrysler states) then that wire is shorted to ground and needs to be repaired before replacing the SBEC.

I followed the flow chart and everything you did is correct and leads to Replace SBEC, we are only as good as the service info provided.
I have never (Knock On Wood!!!) had a VNT Solenoid failure so I do not have any past experiences to draw on.
If it were my car and I followed the flow chart as you did and it led to replace SBEC then I would be looking for one.
FWD Performance, Parts Wanted Section, etc.
 

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Discussion Starter #15
I did have the SBEC and solenoid disconnected when I measured the resistance of the ground wired between pin 36 connector and the solenoid connector and got 1.6ohm. Or, if I am understanding you correctly, I need to measure resistance at Pin 36 of the SBEC connector and body ground while the solenoid is still disconnected and see if there is a path to ground somewhere in the wiring loom? If it reads open, the wires fine, if it sees resistance then I have an issue somewhere.

FWD Performance still active, as their website doesn’t look too updated. I see they have a VNT Stage 2 SBEC for sale and I may just jump on it.
 

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Yes, you will check resistance of Cavity 36 to ground with both the Solenoid and SBEC connectors disconnected.
With both disconnected the circuit is open, it is no longer connected to anything, the only resistance you should have would be from end to end, not one end to ground.

Not all controllers die on their own, sometimes something in the circuit kills the controller, a short to ground could do this, controllers dying was a huge problem for GM in the late 80's and it took them a while before they figured out why and passed that info on to their techs.
If that wire is shorted to ground, it needs to be repaired.

If it were me and that wire was shorted to ground I would follow the harness to be sure it is secured and not rubbing on something that may have caused the problem and then run a new wire from the SBEC to the Solenoid rather than open the entire harness.
One thing you need to be aware of is engine mounts, especially with more power added, excessive engine movement could be the cause of a harness rubbing through.
When I first got my car back in 90 I was racing her and the 1-2 shift @ 5500 RPM's was hard, threw me back in the seat and I broke the passenger side engine mount three times, actually bent/destroyed the entire bracket assembly.
I do not race/drive hard anymore but about 15 years ago I went with Poly Mounts.

FWD Performance was a vendor on this site for a long time, they are no longer a vendor here, why?
They do have a Facebook Page, is it current?
 

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Discussion Starter #17
I will check the wire resistance to ground this weekend and verify it is open. I went ahead and ordered the Stage 2 ‘89-90 VNT SBEC from FWD Perf. for the heck of it. Can’t argue against a better performance controller. Their website copyright says “2001” on it so that’s why I was asking if they were still operating, but their FB page was updated just last month so they must be.

I will report back if I need to run a new ground wire for the circuit. I already traced the loom and found no damage or points of contact, so I really don’t see how this one wire could be shorted since its basically in the middle of the wire loom.
 

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Hopefully when you recheck the wire this time with both components unplugged you read "open".
 

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Discussion Starter #19
Well yep, checked the wire from SBEC pin 36 connector against the body ground, with the solenoid connector unplugged and it read open. So not a wiring issue. Kind of was hoping I just needed to run a new wire cause now I am going to have to send this SBEC off for repair. FWD Perf. Did not have a VNT computer to tune and send me though they were checking their piles and are going to call me back.
 

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And all the scanner shows is all VNT Solenoids are off with the key on/engine off and they are all on @ 0% with the engine running.
I know you have the code, are you having any boost issues?
Do you have a boost gauge in the car?
Can you get a hold of a scanner to see all solenoid values and boost goal when driving?
 
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