Throttle Failure

[daisu]

Hi all,

Recently (a couple times over the last few months) my skyline has gone into limp mode (VDC/slip lights illuminated, throttle restricted). Each time this happened I was able to turn the car on and off a couple times and it came good.

Last weekend though, I turned the car on and there is absolutely no throttle response, the car starts and idles but will no rev at all.

I pulled the pedal out of the car and tested the resistance on both sides, appeared to be working okay but without a power supply I couldn't verify that it was 0-5Volt.

I borrowed a throttle body but that did not seem to change anything.

Done multiple ECU resets and always coming back with the same 2 fault codes 1122 - Electronic Throttle Control Actuator and 1126 - Throttle Control Motor Relay.

So I pulled the relay out, powered the coil and it seems fine, the contacts are switching. Then I checked the terminals where the relay plugs in. The two pins for the coil had 12V on one pin and 3V on the other pin. 9volt across the coil will not energise the relay.

Does that seem odd to anyone else? That the ECU would raise the voltage on one side to turn the relay off, or is that normal behaviour?

So then I bridge the two other pins in the relay holder, supplying 12V to the other side of the circuit. The throttle now moves (it jumps a little) when you turn the ignition on and it cycled open/close when I turned the ignition off. Still not operating with the pedal though.

Looking around the forums I found a few examples where the Intelligent Power Distribution Module (IPDB, fuse box behind the battery) was at fault. People were describing that it looked like it had been exposed to water. So I have a look in behind the battery, there was a puddle of water there because the drain was blocked with dirt/leaves. There was no obvious evidence that the IPDB had been submersed but it may have happened. It looks like it is supposed to slide out of the base but I couldn't figure out how to release the clips.

The car is running a haltech platinum pro (plug-in piggy back), so I'm planning to disconnect that tomorrow and rule that out. Otherwise hoping the service manual will shed some light, (I'll try to come down to the shop and see you Chris).

I couldn't figure out how to release the plugs on the ECU, it looked like there was a screw that needed to be turned 90degrees but I couldn't find a suitable tool to turn it.

Edited July 3, 2011 by daisu

[bosco]

I am having the same issue as well after installing a throttle control unit... The vdc and slip light is on... And will not rev... The car will only limp... Why is that?

[daisu]

The ECU does not like your throttle control unit. Have you tried resetting the ECU?

[scotty nm35]

I had the same thing happen occasionally with my Pivot throttle controller, and difference in the resistance curves and it goes into throttle limp, 1200 revs. I have it on "normal" now with no problems in the last 6 or so months.

Luke, I have a cable throttle setup for the VQ if you want too try it.

[daisu]

Disconnected the factory ECU to remove the plug in haltech and found water inside the factory ecu socket. There was a heap of corrosion and one of the ECU pins has snapped off inside the plug.

Edited July 4, 2011 by daisu

[bosco]

Mines is on normal now and drives fine... As soon as I put it in a different setting it goes into limp...anyway I can fix this?

[daisu]

How do these throttle controllers work? Do they modify the signal from the pedal to the ECU or do they modify the signal from the ECU to the throttle body?

Have you tried resetting the ECU and doing the pedal/throttle relearn things?

[bosco]

I am pretty sure these controller amplify the throttle singal to make you feel the car is going faster.... but really just fooling myself lol... yes i did reset the ecu and it will be fine but when I turn the controller on it will limp again

[daisu]

I am pretty sure these controller amplify the throttle singal to make you feel the car is going faster.... but really just fooling myself lol... yes i did reset the ecu and it will be fine but when I turn the controller on it will limp again

I mean specifically, have you tried turning the controller on (it then goes into limp mode) and then reset the ECU with the controller still set, so that the ECU will learn the pedal/throttle with the controller on?

You would imagine that it would have to work somehow? What brand is it? You could ask for a refund, product is unfit for purpose if it can't adjust the throttle without sending it into limp mode.

[bosco]

Yeh I tried that... But still goes into limp... I sucessfully made it work... But after awhile it goes into limp... The brand is called shadow... Pretty big in the states...

[daisu]

Maybe the USDM ECU's are less sensitive to adjustments on the throttle signal.

[black 350]

hi everyone, i have a 350gt manuel sedan and have just put on some extractors and hi-flow cats on. and my (VDC) off is displayed and (slip) is now constantly lit up usally only lights up once traction is broken vdc on ofcourse. it only comes on once i start to move, evan if i leave vdc on slip will light up. also it must think that its out of control as the front brakes r breaking for me before the slip showes up. its getting very frustrating, if any one could light would be much appriceated.

[scotty nm35]

Check the front wheel speed sensors (behind the disk) are in place and follow the wire up to see if it has been unplugged. Also check it's not melting on the extractors? Then make sure the rear ones are ok.

If the car is braking then the system is working, just not seeing the proper sensor inputs I would say.

Good luck, it sounds annoying.

[tehmessiah]

Hi, I too have a similar issue except I have no mods.

I drove the car to work this morning with no issues and when I went to leave just now the car idles but I have no accelerator. The check engine light and VCD are on. Turned it on and off, locked it and unlocked it but nothing fixed it.

For a while now the drivers window won’t go down and some times the vcd light stays on but it usually goes away.

 Any help would be appreciated please?

 

[tehmessiah]

According to the tow truck driver it’s a common issue with Nissans.

[Vee37]

I now recently got a 370GT, but for the last 11 years, I had a 350GT. At one stage, I had a failure of one of my ignition coils. When the car warmed up, the rough idle and misfire went away. The weird thing for me was that the ignition coil fault code actually triggered the VCD warning light. Until fixed it, I would clear the code after warming up, turn off and restart the car, and it would work as normal.

 

I guess my point is that one fault can trigger other warnings that seem totally unrelated. I guess that may be related to a limp mode.

Edited February 8, 2022 by Vee37