What is it, why is it there, how to does it work and why?
My engine stalls (shuts down) at anytime, or even cranking, why?
All comments are USA, not Export Jeeps.
Real JEEPS ! ONLY ! (all EFI cars have this but is executed in diferent ways)
On most cars the ASD is just sofware in the ECU/PCM. On jeeps its both , Software and Hardware , the ASD relay. (to me, they are all the same)
ASD "Automatic Shut Down relay" used on all EFI jeeps. 1990 to present.
what is it?
It is a safety device, that exists by LAW and for good reasons. It prevents FUEL fires (the Classic Crash and burn reason) and engine hyrdolocking.
It does that by cutting fuel, spark and injection. (via hardware and software) (software means the PCM(ECU) instructions , in ROM)
It cuts fuel (and spark) if the PCM thinks, there is any danger of crash and burn.
The PCM drops the ASD for many reason, this list is for all years. (some are missing on early years)
1: Sees the spark weak or dead on the ignitor drive to Igniton coil primary pin. (it knows spark is bad) (It can't see the secondary High Voltage side, just the primary)
2: Crank sensor bad. or misfiring. CKP
3: Cam sensor bad, or misfiring , CMP.
4: ASD input read back pin fails. (PCM commanded it but it refused to do its job) Shorted relay coil?
5: Same ASD output read back. fails. PCM commanded it, but the relay is bad. dead output . (bad RELAY)
6: Immoblizer active. (failing or bad IMMO key, etc,) SKIM module is unhappy see dash light glowing telling you, SKIM failure. Any security flailures, at all will glow the idiot lamps. The operators guide is clear there, read that .
7: On some newer years, the fuel pump relay output is monitored and if it fails. It sets DTCs and drops the ASD.
On even newer Jeeps with Throttle by wire, it might shut down with a catastophic throttle by wire (TBW) T-body motor error or TPS stuck open on all cars, preventing "Toyota Run-Aways" if you get my drift. (lawsuits...)
FACT: In each case the PCM will log errors and show DTC errors, if you only LOOK!
If the ASD drops driving or even parked idling, one of the above caused it. (older cars have, less checks)
The ASD has engine startup logic that is unique to JEEPs. (in part)
You must crank with in seconds or the key on, is ignored by many jeeps. (the ole' key off , key on try again deal) "operators guide explains this"
You crank the engine, and the above 6/7 logic checks, must not fail, during the start event or it cuts the ASD.
Note carefully, if spark is bad cranking, the ASD cuts spark coils 100% dead.(double dead)(funny, but very true ,read the ASD schematic) (the ECU gives but 2 seconds to wake up and work, or kills the show)
You only get 2 seconds to get the 6/7 factors true or the game is all over.
If when driving, it (PCM) sees one of the 6/7 fail, ASD drops.
In fact, the ASD can drop, then come back, while driving, people say it cuts out. sure it did, on 1996 and newer cars you can scan , drive and log to see why ! any OBD2 scan tool. one that logs is, best of best.
The USA has all cars OBD2 1996 and newer and cheap scan tools can be had for $9, rented or loaned to you. (there is no reason to work blind ever in the USA, get the scan tool , plug it in and USE IT) (if older use the blinking CEL)
The DTCs tell you. Cmp /ckp or spark dead. (and unique codes for ASD failures input or outputted)
OBD2 we check Pending or live DTC's.
Freeze frame, DTC will show what failed.
and even seeing RPM drop like a rock, faster than any crankshaft can spin down, dig? is one more clue.
Loss of 12vdc power to the PCM , kills EVERYTHING. I monitor the CIG lighter with voltmeter, even driving. My scan tool can monitor, PCM power. (it has a unique PID for that) Pids are live data from sensors. Parameters IDs.
On pre 1996 Jeeps you have to learn to do the FLASH CEL lamp tests.
The FSM covers that under emmissions + diagnostics. See DTC list and how to get it. (hint :crank for 5 seconds, see what fails?)
the FSM is here
http://www.jeep4x4center.com/knowledge-base/index.htm?utm_source=cj#service
DTC methods from first Jeeps to new.
The igntion key toggle tricks works 1991? to now., 1996+ Jeeps, a scan tool must be connected to the OBD2 port to diagnose any ASD issues, below is a list of codes that will shut it down. (OBD2)
Key trick is (On/off/On/off/On/ ) see CEL (MIL) flash 2 digit codes now.... "no start? crank for 5 seconds., release key and see codes ? might work too.?"
Jeep changes codes like gals change lips stick colors.
All decimal codes, FSM uses hex. (base 16)
Warning, the CEL may not glow for many errors running. even code 54 will not glow the CEL. (scan tools rule here)
At the end it will flash two fives, which means end of codes
DTC's:
- 11 CKP crank sensor dead. 1996/7 (P1391) (P1398) misfire at limit !
- 24 TPS stuck high, cuts fuel. (P0123)
- 42 ASD fails up to 1998 or can mean the Fuel pump relay output is DEAD. See FSM for details.
- 43 dead spark (prim side) (P0351) and P030x misfires.
- 54 (1993 my oldest book) no cam sync, CMP. (1996/7)
- 157 (9D-hex? DRB?) (P1391) cmp/ckp loss. (1998+ code)
- I'm sure there are other codes that can drop ASD but jeep does NOT list them all. Thus my page.
- 37
Park / neutral switch PRNDL failure? (I'm guessing here) and beyond
here. code 14/24/? The jeep books do a poor job of stating
all ASD logic. IMO !
Dog chases trail ?:
Please do not take your car to the dealer and say , my CEL was on, before, but not now. oops !
The PCM only reports live codes (old codes are cleared automatically if no longer true) (Live means NOW)
In the real world, things can be good, bad or intermittant. (buy a scan tool and log your failures in real time live, and then you have facts that can solve complex problems)
AND
The ECU stores codes, but if they self corrected, they are ERASED, (sorry the dealer can NOT see erased codes by the PCM or by your resetting them with the scan tool or battery pulls) (there is no Windows undelete command, in cars, not yet....)
If you ask them to fix cleared codes, at the dealer you will spend lots of cash and get zero results. (it's an Implied, demand by you; for him to GUESS, so you are asking him to guess, he is not god. nor clairvoyant, he is but only a man)
So, buy a $9 scan tool and get the DTCs your self ,write them down and the mechanic can guess 10 times better now. even 100 times is possible (eg, intermittent open 02 sensor heater. for sure)
One more odd thing is the ECU/PCM on most cars loves to hide bad spark DTCs, you key off and it erases the bad spark DTC. (this is to give it a new chance, next crank up, IMO)
More..... (one more case of the chicken and egg) see why?
The older Jeeps, say a 1995, has OBD1, and most folks don't have a Scan tool.
The key on/off/on/off/on trick erases spark failure codes.
On 1991 and newer Jeeps, the scan tool can see bad spark DTCs. (try it)! Cranking for 5 seconds. Look for Spark fail or other codes. (DTCs)
This tool can do real scans on 1993/1995 Jeeps.
Older than that , only $1000 and up scan tools work,
DRB2,
Snap-On MT-2500.
The older 87-90' Renix EFI (ECU) will not even store codes, it only does live errors.
Buy an old DRB2, off fleabay. 91 up 95?
AutoXray 5000, or 6000 used
OTC monitor 4000 , used.
Actron CP 9110
RENIX history:
Model years: (find a working scan tool for these engines, is problematic. )
The Renix EFI is AMC system. its not a JEEP it's AMC. and is NOT OBD1 at all. (it's pre OBD1 or as they say Proprietary.)
- 1986 - Renix TBI available on Jeep 2.5 L four-cylinder engines.
- 1987 - the new Renix controlled 4.0 L six-cylinder engine was rated at 173 hp (129 kW; 175 PS) and 220 lb·ft (298 N·m) of torque.
- 1988 - 4.0 L output increased to 177 hp (132 kW; 179 PS) and 224 lb·ft (304 N·m) of torque, due to higher compression ratio.
- 1989 - Changed to Renix MPFI.
- 1991 - Chrysler Corporation (then the owners of the Jeep brand replaced the Renix control system with OBD-I-compliant control electronics, the Chrysler HO EFI).
Jeep History helps.
The marque has gone through many owners, starting in 1941 with Willys, which produced the first Civilian Jeep (CJ).
Willys was sold to Kaiser in 1953, which became Kaiser-Jeep in 1963.
American Motors (AMC) bought the company in 1970.
The Chrysler Corporation bought out AMC in 1987, shortly after the Jeep CJ was replaced with the AMC-designed Jeep Wrangler or YJ.
Finally, Chrysler merged with Daimler-Benz in 1998 to form DaimlerChrysler.
and now is Fiat in 2009.
They did continue to use "AMC" parts until the stock was depleted.
wow !
by : fixkick.com
Just fast journal here, for friends with bad ASD,...
rev 2 ++++ 3-15-2011