Pulled ECM and put back in...car will not start.

carboncow · Post by **carboncow** » 02 Apr 2018, 17:52

We are thinking we have a bad ECM due to the list of error codes in VIDA. Took battery offline, wait 5-10 minutes, discharged cables and lights were on...power should be disputed. Took out ECM and companion module up front to inspect connectors, wires and anything we can see in that area. Figured we'd send out the ECU for inspection/repair.

In the mean time we slapped it back to move car....but now just turns over and will not catch. Acts like no spark/fuel.

Anyone know what we did wrong? Is there a process to putting the ECM back in I didn't trip over?

We'll pull it again and reseat tomorrow and make sure we didn't mangle a pin but I'm sure the locking system would prevent this.

Thoughts? A bit concerned!

Post by **RickHaleParker** » 02 Apr 2018, 18:20

Other then a dective ECM, the only think I can think of is low voltage or poor ground messing up the timing in the ECM or a defect in the CAN bus between the ECM and CEM.

Did you clean the connector when you had the ECM out?

1. Go to the search tab.
2. (✔) All information except parts catalog
3. Search for ECM-711A
4. (✔) Diagnostic trouble code (DTC) information

284: ECM-711A Engine control module (ECM), internal fault. Signal too high / signal too low. Permanent fault

Diagnostic trouble code (DTC) information

D2800349 Condition
Diagnostic trouble code (DTC) ECM-711A is stored if the engine control module (ECM) registers a fault in the internal circuit for the timer in the control module.

Substitute value
None.

Possible source
Faulty signal:
Defective control module.

Fault symptoms
The malfunction indicator lamp (MIL) lights.

Post by **abscate** » 02 Apr 2018, 19:08

I think one of the 2 ECU failures we have had on MVSwas in Ohio, but I’m sure that was a coincidence

ECU trouble is at the bottom of a very long diagnostic chart.

Did you hamdle it with ESD protection? If not, removing it was a bad idea

Post by **chrism** » 03 Apr 2018, 06:13

I don't know if it's even possible, but is there any chance you got the ECM and TCM swapped? (TCM=Transmission Control Module)

Did you use the "U" shaped tool to unlatch/relatch the modules?

carboncow · Post by **carboncow** » 03 Apr 2018, 18:01

Once again I'm not getting notifications for your posts...so thanks and I'm a day short. I've attached the recent Vida scan and as you can see the comm with TCM and ECM is not showing up now.

1. No I didn't use the tool. As seen all over the inter tubes it can be done without the tool but now I'm starting to wonder w/o that tool if one cannot get it properly locked into place to make connectors meet the module? Anyone know this from experience and not guessing?
2. No I didn't use ESD protection. They are not that sensitive no matter what everyone try to tell you. The chance of losing both modules defies stats since I've been pulling ECU for 20 years w/o issue as well as working with computers for 30 years with out ESD damage. Directly touching chips is another thing.
3. Also, I take photos of everthing before I start pulling apart...so great guess on getting the modules backwards...but no luck!
4. I've got fine voltage showing on vida dice...trust me if vida dice has enough power to run then the car does. Learned that from 10+ years of arguing with vida dice on older cars!

We just spent another hour down there and can get them in/out just fine but I see how the locking system is only at 50% w/o the tool. Not really sure how the tool can pull it down any tighter unless I'm missing what the pink sliders do on the inside connection.

No need to clean connections as they were spotless. No sign of damage or corosion I'd just like to get the car back to somewhat working modules even if I have the ECM errors...I need my garage back!

So unless anyone has any better ideas I'm going order the damn tool and hoping that jamming it back in there tighter will have some impact.

Post by **chrism** » 05 Apr 2018, 11:46

I tried to remove my ECM once without the tool (using a long skinny screwdriver) and couldn't do it. All I accomplished was making matters worse and had to have the car towed to a shop to have it unlatched/relatched. As the pink sliders move, they pull the module down tighter into the seat. Notice how the four channels are slanted in the photo linked below below (in the black base part).

If you have a Haynes manual for P2 cars, it has a diagram showing how to build your own tool. Haynes shows just making it a "single-sided" tool, meaning you would have to move one slider a bit, flip the tool to the other slider and move it a bit, back-and-forth until both sliders are fully moved. Or you could get fancy and build the tool as a double sided U-shape like the ones you buy. FYI - I saw one on the Walmart websight a few months ago for about $14. They seem to be getting cheaper as time goes on.

http://i.ebayimg.com/images/i/301716085 ... -l1000.jpg

01_Nautic_V70 · Post by **01_Nautic_V70** » 05 Apr 2018, 13:06

In troubleshooting this, I'd look for what's common to both modules.

If there's no communication to either module, the power is off to that box or the CANbus leads are messed up. CANbus is a serial, two-wire protocol, so if one lead is broken or has a pushed pin, there's no comms to either.

The wiring harness to those modules is combined. I assume there's a combined +12VDC and GND connection to those two connectors?

Post by **abscate** » 05 Apr 2018, 14:02

Ive removed ECMs on the 1999 with a screwdriver but not sure the P2 platform is the same. The pink lock slide slid easily back into full lock. It sounds like it isnt seated right.

Post by **mrbrian200** » 05 Apr 2018, 14:27

CANbus wires loop through the TCM on its way to the ECM. 2 wires in, 2 wires at separate positions on the connector out. If the TCM isn't seated the ECM won't be on the network either.

Only on MT cars the CANbus wires run directly between the CEM->ECM.

Modules on the P2s can be removed/reseated without the tool if you're really determined, but its tricky. I probably wouldn't recommend trying it.

I did it once. But I ended up pulling the headlight assembly out so that I could push on the slide/lock mechanism with a screwdriver from the end in order to get the module to seat/lock fully.

Use of the proper tool is advised.

Post by **abscate** » 06 Apr 2018, 05:13

Get the TCM andECM reseated fully. The ECM experts can chime in as to if the yellow light loss of signal is a fatal or minor error. I’ve seen threads where that error is reported on running cars.

Was the car starting before the control units were removed? What was the history leading up the no-start