I'm having that common problem - The car runs like **** in the cold mornings until it warms up. It's not the blue temp sender this time because I've just bought a genuine one. It could well be the ECU. Problem is, I don't how to check it or even how to use my multimeter! I'd appreciate it if you could tell me what function I should set the dial on? Thanks all!
An ECU is a computer. You don't test it with a multimeter. If you mean checking that the sensor signal is getting back to the ECU. Unplug it. Find the correct pins. Measure resistance into the harness/sensor. Ohms < 1000 range. Best you know what you are doing though! Jon
Follow this thread to set the car up after fitting a blue sender. http://www.clubgti.com/showthread.p...your-Digifant-GTI-8v&highlight=reset+digifant To check the sensor is working correctly, you can unplug the sensor, and warm the car while checking for change of resistance across the sensor terminals. So meter on ohms on a setting to suit the greatest/highest reading and follow the chart as the car warms up.
find the setting that sits at 1 with probes apart then drops to 0 when they touch, or better yet the setting that beeps when you touch the tips if you have this feature! then got from each pin on the ecu to the relevant pins on the other end of the loom, this checks each wire for continuity: 4 - knock sensor pin 1 5 - knock sensor pin 2 6 - brown/white - dizzy pin 1/- and throttle switch, and coolant temp sensor pin 2, and AFM pin 4 7 - knock sensor pin 3 8 - red/black - dizzy pin 3/+ 9 - blue/white - AFM pin 1 10 - brown/green - coolant temp sensor pin 1 11 - red/blue - throttle switch 12 - brown/yellow - fuel rail pin 2 13 - brown - battery -ve 17 - blue/black - AFM pin 3 18 - green/white - dizzy pin 2/o 19 - brown/black - earth to head 21 - blue/red - AFM pin 2 22 - yellow -isv pin 1 23 - white - isv pin 3 25 - green - TCI pin 6 TCI unit: 1 - red/black - coil -ve 2 - brown/white - battery -ve 4 - black - coil +ve 6 - green - ecu pin 25 Then switch it to the voltage test mode (so that it shows 12.5ish when you put it on the battery terminals) put the -ve probe on the battery -ve then test these 2 pins: 1 - red/green - cranking live 14 - black/yellow - ignition live while you're there check the overall condition of the wiring, look for black tape, dirty earth points and check all the pins inside the plugs to ensure they're not pushed back or bent. dont forget to peel the rubber boots back on the plugs to see the condition of the wires underneath. then its a case of all the usual checks, make sure service components all good, check inlet boot, vacuum pipes and PCV valve bung etc for vacuum leaks, check idle screw oring is good, check idle switch clicks throttle closed and throttle switch wiring is all ok, check ignition and basic idle setting etc
Whats wrong with a good old fashion continuity test most people can do that with a multimeter ,certainly a good start ?
Thanks for your advice chaps. I only got the chance to test it today. I tested the blue temp sender and the readings were Brown/Green - 0 White/Brown - 0.7 Please advise!
I'm really stuck on this. If I take the sender out while the engine is on it runs like a pig and cuts out after a few seconds. If I test the wires while the engine is t running, I get a reading of 0.7 on the WhiteBrown and 0 on BrownGreen. Also, I've been putting the black prong onto a bare metal patch of the engine. Please explain in simple terms on how to test my temp sender! Thanks all.
Right, just tested from temp of 50 to 90 and the reading averaged 230. This was on the WhiteBrown. The BrownGreen always reads as 1. What does this mean? Thanks again.
Thanks mate. The readings followed the chart. Does this mean that my cold start problems are now down to the sender?
yeah seems sensor is fine, go back to the ecu connector and measure again with blue sender connected between pin 6 and 10. if readings are the same as they are at the sensor then the wiring and sensor is fine. if not, check the wiring between ecu and sender
Is that on the right of the ecu? (Looking at from the front of the car? I've got loads of blue tape everywhere from the prev owner. Does it slid off.or there a clip or something? I really appreciate your knowledge a d patience here mate!
on the ecu plug sorry, as per the pinout list above theres a metal clip you release and it pops off, you may have to loosen the ecu bracket to get enough bending room: http://www.clubgti.com/showthread.php?206792
Cool. I'll try that in a minute. It's just started chucking it down here and Ive come inside because I rust easily.
Have I got this right? Disconnect the plug from the ecu and put a prong on Pin 6? The car wont start then though.
yeah disconnect ecu and check the resistance between pin 6 and pin 10 with the blue sender plugged in. if the resistance is the same or close enough as the resistance between the blue sender pins direct then your wiring is ok, if not then there is an issue inside the loom somewhere
Sorry RJ - The car won't start without the ECU plug connected. In anycase, my ECU only has 7 pins. I think I'm missing something crucial here......like a brain. lol
