solved:FP/ prime pulse delayed/ECU won't wake up

[markvwguy]

I have a MS1 V3.0 board built in 2007-2008, I'm struggling with the ECU not waking up and priming the FP cosistantly. It can take 2-10-15-20 seconds for the FP prime/ wake up. Sometimes I have to wait over night. I recently switched to my second MS1 chip (newly flashed) and the same results. 5v and 0v present on the 40 pins socket in the correct places.

Yesterday while driving the ECU "died". I cycled the ignition many, many ,many time over an hour sitting on the road side trying to get it going. Also, as expected Tuner Studio would not access the ECU as well. I was stuck I called AAA for a tow.

I took the ECU to work and plugged it into the JimStim and woke up as normal. Got home plugged it back into the car started fine.

Today, I replaced the 37 pin Harness plug just to make sure and updated some grounding methods (wanting to do that for a while now). When I finished the same problem. Thinking I make and error in my harness I plugged into the JimStim, it did not wake up. I reinstalled it into the car and it finally... took 5-10 seconds to wake up, but it did . I did not make any soldering mistakes. the car runs fine. now it takes maybe 2 second to wake up after power up.

I'm stump the ECU has almost 10,000 miles on it. It has work well over the years. Please help!!! Please advise!! This is the short version of my struggle.

Mark

[Matt Cramer]

See if the ECU has 5 volts on VREF before it "wakes up".

[markvwguy]

Presently, on power up I have instantaneous +5v on the (db37) pin26 vref during FP prime. The unit is waking up OK now. When it does not wake up I will have to check again.

Thank you Matt

[markvwguy]

Yes,
VREF has a solid +5v before the ECU's delayed responds/ wakes up. The measurement taken from the harness 12 inches from the ECU. This morning, the ECU was installed in the car, showed the symptom, unplugged it; than directly plugged to the JimStim same problem would not give the prime pulse/ would not wake up. 10 minutes later still on the JimStim started working OK. The ECU has been on the JS all day no symptoms . I have cycled the ECU many times on the bench still working OK.

Are there any O'scope "shots" to look at during power up, to see if a charge curve is not correct, browning out the MS1? Or, charge not dissipating leaving enough potential to brown out the ECU?

[DaveEFI]

I''s first check you have 5 volts going everywhere it should. You'll find a list of test points in the manual. If that is OK, check the grounds to the daughter board. My guess is you have a dry joint somewhere.

[markvwguy]

Yes, according to the manual,
U1 installed measurements taken from the IC legs
pins 1,20,31 have +5v, while the ECU does not wake up, with respect to pins 2,19,32 ground returns. Measurements check all 18 combinations from one respect to the other, all measurements taken when the ECU would not function.

Presently, ECU waking up OK again.

Mark

[slow_hemi6]

Mike need to check carefully the components and connections involved in the clock circuit.

[markvwguy]

Y1 was not staked down( glued or soldered). Since I have soldered the can to the pad it seems to function with consistency.

Still no issues been driving the car daily

Thank you so very much