Volkswagen Passat Forum banner

Limp Mode 99 Wagon 1.8

2K views 12 replies 8 participants last post by  VAGguy 
#1 · (Edited)
Hey VWers

Looking for some advice / suggestions from any with more know how than I which is probably most of you :)

So I'm pretty sure my wagon is in Limp Mode by the gears in the dash all being highlighted black.
It happened the other day and I didn't pay it much mind as it soon went away.

Little while after I was driving to a friends and there was a big clunk (thought I hit something) and the gears were all highlighted again although the car still drove fine @ 100km/hr getting home.
Unhooked the negative cable for the night and it went back to normal but then reverted back to black after starting it again after a short 10min trip.

Now I'm also noticing pretty hard changes when putting the gear into drive or reverse.
Should note that it's a tiptronic transmission and I've never used the tiptronic in the last 5+ years of owning the car.

Using a VAG Com adapter I'm getting the following codes in this order:

P1746 = Transmission Control Unit Relay, Malfunction
P1136 = Long Term Fuel Trim Add. Fuel B1 System Too Lean
P1476 = EVAP Control System LDP Malfunction/Insufficient Vacuum

After researching P1136 and P1476 to me looks like I should change fuel filter and go over hoses and clamps and connections.

Could error P1136 and P1476 lead to issues with the TCM as well or is that most likely it's own issue entirely?
If no is there a direct way to test TCM?

Also would I be crazy if need be to drive this to my mechanic about 15mins away?

Any suggestions or recommendations greatly appreciated.

Cheers
 
See less See more
#3 ·
When using VAG-COM, did you get that code from the transmission controller? Doesn't seem very specific. The hard shifts are likely because in limp mode, the variable solenoid valves operate in a more on-off fashion, rather than proportional (by pulse width modulation). I'd start with checking the connections at the TCM under the carpet, and at the transmission near the left inner CV joint.

P1476 means that the LDP isn't running properly when it's supposed to. This pump is powered by "vacuum" so any leaks between the pump and the intake manifold can be the cause. Look at the check-valve for the LDP under about the middle of the intake manifold to be certain that it isn't broken. Also, the air flow through the check valve must be towards the manifold, unlike what the incorrect vacuum diagram shows.
 
#4 · (Edited)
Much appreciated for the suggestions / direction PZ and ylwagon

Didn't find anything obvious searching for a vacuum leak with the eyes and the ears but I suppose that's not a proper enough test.
I did pull out the MAF sensor to have a look and have given it a clean, letting it dry out now.

ylwagon - In all honesty I just got the VAG-COM adapter today so it's the first time I've used it.
I plugged in up under the steering wheel.
There is what looks like another spot beside the handbrake but it doesn't have an actual plug just the shape of the plug.

I'll pull up the carpet and take a look at the connections in there and at the transmission next and then on to the check-valve as suggested.

Cheers
 
#7 ·
Hey All

So quick update - as mentioned I had cleaned the MAF Sensor and that had actually cleared up the issue the last couple trips but it came back again and is still switching itself on and off periodically after short trips.

I've not had the time to dig in much further myself so I resorted to taking it into my mechanic who is unfortunately stumped himself although he's convinced it's electrical.

So he's:
1) Topped up the tranny fluid (said it took quite a bit) - also said he wasn't sure how long after a top up it would take to clear out the errors?
2) Checked the TCM and said compartment was wet in there but computer was in a plastic box and dry and he tested connections and all was a-ok
3) Said he's checked the Vacuum and doesn't believe there are any issues there.

He said that he's got the following codes and not sure what to do next so hopefully someone can offer up some suggestions:
18010 - P1602 - Power Supply Terminal 30 Voltage Low / Intermittent
18032 - P1624 - No Request Signal Active
17091 - P0707 - Trans Range Sensor

He said the next thing he was thinking to try was the shift range sensor on the side of the transmission but said it may take a bit to get in there.
Any suggestions on checking that for sure with out tearing it all apart.

Cheers
 
#8 ·
He said the next thing he was thinking to try was the shift range sensor on the side of the transmission but said it may take a bit to get in there.
Any suggestions on checking that for sure with out tearing it all apart.
Yes, but you'll need VAG-COM to watch that the selected gears match the shifter position. If the range switch has to be replaced, I believe that the best approach is to support the transmission while the driver's side trans mount bracket is unbolted and removed out of the way.
 
#11 ·
Looks like it may unfortunately be the end.
Can't seem to get around this damn Limp mode, codes aren't clearing.
There's been some other electric funniness as well, lost ABS awhile back.
Water under the floorboards probably explains why I can't leave the thing locked without the alarm having a mind of it's own.
Too bad really loved the ol girl but it's been one thing after the next for sometime.... it is a 99 tho so that's to be expected.
Weighing over the possibility of having my mechanic dig deeper or just call it quits and start looking for the next beast.
 
#13 ·
Hello, how did you solve the error?
Given the fact that the post above yours was the last time they visited Passat World, I am willing to bet he gave up and disposed of the car without resolution.

If you have a similar problem that you need help with, please start a new thread with as much vehicle/engine/transmission information as possible along with any recent maintenance (even if unrelated) and attempts at diagnosis.
 
  • Like
Reactions: John_E
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top